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author | Charles Harris <charlesr.harris@gmail.com> | 2011-03-14 10:22:02 -0600 |
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committer | Charles Harris <charlesr.harris@gmail.com> | 2011-03-14 10:22:02 -0600 |
commit | cd97607e2f14ac5489215549cb7ff7123394386f (patch) | |
tree | 94e311b36e16ca676b07540ed87d34b8439e7550 | |
parent | 782ba88d601ffe0f2f8373b01279d362d402de8b (diff) | |
parent | c2e4c9c034a3446de643fb4f8e96d21249abb7b9 (diff) | |
download | numpy-cd97607e2f14ac5489215549cb7ff7123394386f.tar.gz |
Merge branch 'poly'
-rw-r--r-- | numpy/polynomial/__init__.py | 3 | ||||
-rw-r--r-- | numpy/polynomial/hermite.py | 1147 | ||||
-rw-r--r-- | numpy/polynomial/hermite_e.py | 1143 | ||||
-rw-r--r-- | numpy/polynomial/laguerre.py | 1146 | ||||
-rw-r--r-- | numpy/polynomial/legendre.py | 46 | ||||
-rw-r--r-- | numpy/polynomial/polytemplate.py | 379 | ||||
-rw-r--r-- | numpy/polynomial/tests/test_chebyshev.py | 6 | ||||
-rw-r--r-- | numpy/polynomial/tests/test_hermite.py | 537 | ||||
-rw-r--r-- | numpy/polynomial/tests/test_hermite_e.py | 536 | ||||
-rw-r--r-- | numpy/polynomial/tests/test_laguerre.py | 530 | ||||
-rw-r--r-- | numpy/polynomial/tests/test_legendre.py | 6 | ||||
-rw-r--r-- | numpy/polynomial/tests/test_polynomial.py | 6 |
12 files changed, 5307 insertions, 178 deletions
diff --git a/numpy/polynomial/__init__.py b/numpy/polynomial/__init__.py index 6b004acc4..32b39aa98 100644 --- a/numpy/polynomial/__init__.py +++ b/numpy/polynomial/__init__.py @@ -17,6 +17,9 @@ from polynomial import * from chebyshev import * from legendre import * from polyutils import * +from hermite import Hermite +from hermite_e import HermiteE +from laguerre import Laguerre from numpy.testing import Tester test = Tester().test diff --git a/numpy/polynomial/hermite.py b/numpy/polynomial/hermite.py new file mode 100644 index 000000000..d266a6453 --- /dev/null +++ b/numpy/polynomial/hermite.py @@ -0,0 +1,1147 @@ +""" +Objects for dealing with Hermite series. + +This module provides a number of objects (mostly functions) useful for +dealing with Hermite series, including a `Hermite` class that +encapsulates the usual arithmetic operations. (General information +on how this module represents and works with such polynomials is in the +docstring for its "parent" sub-package, `numpy.polynomial`). + +Constants +--------- +- `hermdomain` -- Hermite series default domain, [-1,1]. +- `hermzero` -- Hermite series that evaluates identically to 0. +- `hermone` -- Hermite series that evaluates identically to 1. +- `hermx` -- Hermite series for the identity map, ``f(x) = x``. + +Arithmetic +---------- +- `hermmulx` -- multiply a Hermite series in ``P_i(x)`` by ``x``. +- `hermadd` -- add two Hermite series. +- `hermsub` -- subtract one Hermite series from another. +- `hermmul` -- multiply two Hermite series. +- `hermdiv` -- divide one Hermite series by another. +- `hermval` -- evaluate a Hermite series at given points. + +Calculus +-------- +- `hermder` -- differentiate a Hermite series. +- `hermint` -- integrate a Hermite series. + +Misc Functions +-------------- +- `hermfromroots` -- create a Hermite series with specified roots. +- `hermroots` -- find the roots of a Hermite series. +- `hermvander` -- Vandermonde-like matrix for Hermite polynomials. +- `hermfit` -- least-squares fit returning a Hermite series. +- `hermtrim` -- trim leading coefficients from a Hermite series. +- `hermline` -- Hermite series of given straight line. +- `herm2poly` -- convert a Hermite series to a polynomial. +- `poly2herm` -- convert a polynomial to a Hermite series. + +Classes +------- +- `Hermite` -- A Hermite series class. + +See also +-------- +`numpy.polynomial` + +""" +from __future__ import division + +__all__ = ['hermzero', 'hermone', 'hermx', 'hermdomain', 'hermline', + 'hermadd', 'hermsub', 'hermmulx', 'hermmul', 'hermdiv', 'hermval', + 'hermder', 'hermint', 'herm2poly', 'poly2herm', 'hermfromroots', + 'hermvander', 'hermfit', 'hermtrim', 'hermroots', 'Hermite'] + +import numpy as np +import numpy.linalg as la +import polyutils as pu +import warnings +from polytemplate import polytemplate + +hermtrim = pu.trimcoef + +def poly2herm(pol) : + """ + poly2herm(pol) + + Convert a polynomial to a Hermite series. + + Convert an array representing the coefficients of a polynomial (relative + to the "standard" basis) ordered from lowest degree to highest, to an + array of the coefficients of the equivalent Hermite series, ordered + from lowest to highest degree. + + Parameters + ---------- + pol : array_like + 1-d array containing the polynomial coefficients + + Returns + ------- + cs : ndarray + 1-d array containing the coefficients of the equivalent Hermite + series. + + See Also + -------- + herm2poly + + Notes + ----- + The easy way to do conversions between polynomial basis sets + is to use the convert method of a class instance. + + Examples + -------- + >>> from numpy.polynomial.hermite_e import poly2herme + >>> poly2herm(np.arange(4)) + array([ 1. , 2.75 , 0.5 , 0.375]) + + """ + [pol] = pu.as_series([pol]) + deg = len(pol) - 1 + res = 0 + for i in range(deg, -1, -1) : + res = hermadd(hermmulx(res), pol[i]) + return res + + +def herm2poly(cs) : + """ + Convert a Hermite series to a polynomial. + + Convert an array representing the coefficients of a Hermite series, + ordered from lowest degree to highest, to an array of the coefficients + of the equivalent polynomial (relative to the "standard" basis) ordered + from lowest to highest degree. + + Parameters + ---------- + cs : array_like + 1-d array containing the Hermite series coefficients, ordered + from lowest order term to highest. + + Returns + ------- + pol : ndarray + 1-d array containing the coefficients of the equivalent polynomial + (relative to the "standard" basis) ordered from lowest order term + to highest. + + See Also + -------- + poly2herm + + Notes + ----- + The easy way to do conversions between polynomial basis sets + is to use the convert method of a class instance. + + Examples + -------- + >>> from numpy.polynomial.hermite import herm2poly + >>> herm2poly([ 1. , 2.75 , 0.5 , 0.375]) + array([ 0., 1., 2., 3.]) + + """ + from polynomial import polyadd, polysub, polymulx + + [cs] = pu.as_series([cs]) + n = len(cs) + if n == 1: + return cs + if n == 2: + cs[1] *= 2 + return cs + else: + c0 = cs[-2] + c1 = cs[-1] + # i is the current degree of c1 + for i in range(n - 1, 1, -1) : + tmp = c0 + c0 = polysub(cs[i - 2], c1*(2*(i - 1))) + c1 = polyadd(tmp, polymulx(c1)*2) + return polyadd(c0, polymulx(c1)*2) + +# +# These are constant arrays are of integer type so as to be compatible +# with the widest range of other types, such as Decimal. +# + +# Hermite +hermdomain = np.array([-1,1]) + +# Hermite coefficients representing zero. +hermzero = np.array([0]) + +# Hermite coefficients representing one. +hermone = np.array([1]) + +# Hermite coefficients representing the identity x. +hermx = np.array([0, 1/2]) + + +def hermline(off, scl) : + """ + Hermite series whose graph is a straight line. + + + + Parameters + ---------- + off, scl : scalars + The specified line is given by ``off + scl*x``. + + Returns + ------- + y : ndarray + This module's representation of the Hermite series for + ``off + scl*x``. + + See Also + -------- + polyline, chebline + + Examples + -------- + >>> from numpy.polynomial.hermite import hermline, hermval + >>> hermval(0,hermline(3, 2)) + 3.0 + >>> hermval(1,hermline(3, 2)) + 5.0 + + """ + if scl != 0 : + return np.array([off,scl/2]) + else : + return np.array([off]) + + +def hermfromroots(roots) : + """ + Generate a Hermite series with the given roots. + + Return the array of coefficients for the P-series whose roots (a.k.a. + "zeros") are given by *roots*. The returned array of coefficients is + ordered from lowest order "term" to highest, and zeros of multiplicity + greater than one must be included in *roots* a number of times equal + to their multiplicity (e.g., if `2` is a root of multiplicity three, + then [2,2,2] must be in *roots*). + + Parameters + ---------- + roots : array_like + Sequence containing the roots. + + Returns + ------- + out : ndarray + 1-d array of the Hermite series coefficients, ordered from low to + high. If all roots are real, ``out.dtype`` is a float type; + otherwise, ``out.dtype`` is a complex type, even if all the + coefficients in the result are real (see Examples below). + + See Also + -------- + polyfromroots, chebfromroots + + Notes + ----- + What is returned are the :math:`c_i` such that: + + .. math:: + + \\sum_{i=0}^{n} c_i*P_i(x) = \\prod_{i=0}^{n} (x - roots[i]) + + where ``n == len(roots)`` and :math:`P_i(x)` is the `i`-th Hermite + (basis) polynomial over the domain `[-1,1]`. Note that, unlike + `polyfromroots`, due to the nature of the Hermite basis set, the + above identity *does not* imply :math:`c_n = 1` identically (see + Examples). + + Examples + -------- + >>> from numpy.polynomial.hermite import hermfromroots, hermval + >>> coef = hermfromroots((-1, 0, 1)) + >>> hermval((-1, 0, 1), coef) + array([ 0., 0., 0.]) + >>> coef = hermfromroots((-1j, 1j)) + >>> hermval((-1j, 1j), coef) + array([ 0.+0.j, 0.+0.j]) + + """ + if len(roots) == 0 : + return np.ones(1) + else : + [roots] = pu.as_series([roots], trim=False) + prd = np.array([1], dtype=roots.dtype) + for r in roots: + prd = hermsub(hermmulx(prd), r*prd) + return prd + + +def hermadd(c1, c2): + """ + Add one Hermite series to another. + + Returns the sum of two Hermite series `c1` + `c2`. The arguments + are sequences of coefficients ordered from lowest order term to + highest, i.e., [1,2,3] represents the series ``P_0 + 2*P_1 + 3*P_2``. + + Parameters + ---------- + c1, c2 : array_like + 1-d arrays of Hermite series coefficients ordered from low to + high. + + Returns + ------- + out : ndarray + Array representing the Hermite series of their sum. + + See Also + -------- + hermsub, hermmul, hermdiv, hermpow + + Notes + ----- + Unlike multiplication, division, etc., the sum of two Hermite series + is a Hermite series (without having to "reproject" the result onto + the basis set) so addition, just like that of "standard" polynomials, + is simply "component-wise." + + Examples + -------- + >>> from numpy.polynomial.hermite import hermadd + >>> hermadd([1, 2, 3], [1, 2, 3, 4]) + array([ 2., 4., 6., 4.]) + + """ + # c1, c2 are trimmed copies + [c1, c2] = pu.as_series([c1, c2]) + if len(c1) > len(c2) : + c1[:c2.size] += c2 + ret = c1 + else : + c2[:c1.size] += c1 + ret = c2 + return pu.trimseq(ret) + + +def hermsub(c1, c2): + """ + Subtract one Hermite series from another. + + Returns the difference of two Hermite series `c1` - `c2`. The + sequences of coefficients are from lowest order term to highest, i.e., + [1,2,3] represents the series ``P_0 + 2*P_1 + 3*P_2``. + + Parameters + ---------- + c1, c2 : array_like + 1-d arrays of Hermite series coefficients ordered from low to + high. + + Returns + ------- + out : ndarray + Of Hermite series coefficients representing their difference. + + See Also + -------- + hermadd, hermmul, hermdiv, hermpow + + Notes + ----- + Unlike multiplication, division, etc., the difference of two Hermite + series is a Hermite series (without having to "reproject" the result + onto the basis set) so subtraction, just like that of "standard" + polynomials, is simply "component-wise." + + Examples + -------- + >>> from numpy.polynomial.hermite import hermsub + >>> hermsub([1, 2, 3, 4], [1, 2, 3]) + array([ 0., 0., 0., 4.]) + + """ + # c1, c2 are trimmed copies + [c1, c2] = pu.as_series([c1, c2]) + if len(c1) > len(c2) : + c1[:c2.size] -= c2 + ret = c1 + else : + c2 = -c2 + c2[:c1.size] += c1 + ret = c2 + return pu.trimseq(ret) + + +def hermmulx(cs): + """Multiply a Hermite series by x. + + Multiply the Hermite series `cs` by x, where x is the independent + variable. + + + Parameters + ---------- + cs : array_like + 1-d array of Hermite series coefficients ordered from low to + high. + + Returns + ------- + out : ndarray + Array representing the result of the multiplication. + + Notes + ----- + The multiplication uses the recursion relationship for Hermite + polynomials in the form + + .. math:: + + xP_i(x) = (P_{i + 1}(x)/2 + i*P_{i - 1}(x)) + + Examples + -------- + >>> from numpy.polynomial.hermite import hermmulx + >>> hermmulx([1, 2, 3]) + array([ 2. , 6.5, 1. , 1.5]) + + """ + # cs is a trimmed copy + [cs] = pu.as_series([cs]) + # The zero series needs special treatment + if len(cs) == 1 and cs[0] == 0: + return cs + + prd = np.empty(len(cs) + 1, dtype=cs.dtype) + prd[0] = cs[0]*0 + prd[1] = cs[0]/2 + for i in range(1, len(cs)): + prd[i + 1] = cs[i]/2 + prd[i - 1] += cs[i]*i + return prd + + +def hermmul(c1, c2): + """ + Multiply one Hermite series by another. + + Returns the product of two Hermite series `c1` * `c2`. The arguments + are sequences of coefficients, from lowest order "term" to highest, + e.g., [1,2,3] represents the series ``P_0 + 2*P_1 + 3*P_2``. + + Parameters + ---------- + c1, c2 : array_like + 1-d arrays of Hermite series coefficients ordered from low to + high. + + Returns + ------- + out : ndarray + Of Hermite series coefficients representing their product. + + See Also + -------- + hermadd, hermsub, hermdiv, hermpow + + Notes + ----- + In general, the (polynomial) product of two C-series results in terms + that are not in the Hermite polynomial basis set. Thus, to express + the product as a Hermite series, it is necessary to "re-project" the + product onto said basis set, which may produce "un-intuitive" (but + correct) results; see Examples section below. + + Examples + -------- + >>> from numpy.polynomial.hermite import hermmul + >>> hermmul([1, 2, 3], [0, 1, 2]) + array([ 52., 29., 52., 7., 6.]) + + """ + # s1, s2 are trimmed copies + [c1, c2] = pu.as_series([c1, c2]) + + if len(c1) > len(c2): + cs = c2 + xs = c1 + else: + cs = c1 + xs = c2 + + if len(cs) == 1: + c0 = cs[0]*xs + c1 = 0 + elif len(cs) == 2: + c0 = cs[0]*xs + c1 = cs[1]*xs + else : + nd = len(cs) + c0 = cs[-2]*xs + c1 = cs[-1]*xs + for i in range(3, len(cs) + 1) : + tmp = c0 + nd = nd - 1 + c0 = hermsub(cs[-i]*xs, c1*(2*(nd - 1))) + c1 = hermadd(tmp, hermmulx(c1)*2) + return hermadd(c0, hermmulx(c1)*2) + + +def hermdiv(c1, c2): + """ + Divide one Hermite series by another. + + Returns the quotient-with-remainder of two Hermite series + `c1` / `c2`. The arguments are sequences of coefficients from lowest + order "term" to highest, e.g., [1,2,3] represents the series + ``P_0 + 2*P_1 + 3*P_2``. + + Parameters + ---------- + c1, c2 : array_like + 1-d arrays of Hermite series coefficients ordered from low to + high. + + Returns + ------- + [quo, rem] : ndarrays + Of Hermite series coefficients representing the quotient and + remainder. + + See Also + -------- + hermadd, hermsub, hermmul, hermpow + + Notes + ----- + In general, the (polynomial) division of one Hermite series by another + results in quotient and remainder terms that are not in the Hermite + polynomial basis set. Thus, to express these results as a Hermite + series, it is necessary to "re-project" the results onto the Hermite + basis set, which may produce "un-intuitive" (but correct) results; see + Examples section below. + + Examples + -------- + >>> from numpy.polynomial.hermite import hermdiv + >>> hermdiv([ 52., 29., 52., 7., 6.], [0, 1, 2]) + (array([ 1., 2., 3.]), array([ 0.])) + >>> hermdiv([ 54., 31., 52., 7., 6.], [0, 1, 2]) + (array([ 1., 2., 3.]), array([ 2., 2.])) + >>> hermdiv([ 53., 30., 52., 7., 6.], [0, 1, 2]) + (array([ 1., 2., 3.]), array([ 1., 1.])) + + """ + # c1, c2 are trimmed copies + [c1, c2] = pu.as_series([c1, c2]) + if c2[-1] == 0 : + raise ZeroDivisionError() + + lc1 = len(c1) + lc2 = len(c2) + if lc1 < lc2 : + return c1[:1]*0, c1 + elif lc2 == 1 : + return c1/c2[-1], c1[:1]*0 + else : + quo = np.empty(lc1 - lc2 + 1, dtype=c1.dtype) + rem = c1 + for i in range(lc1 - lc2, - 1, -1): + p = hermmul([0]*i + [1], c2) + q = rem[-1]/p[-1] + rem = rem[:-1] - q*p[:-1] + quo[i] = q + return quo, pu.trimseq(rem) + + +def hermpow(cs, pow, maxpower=16) : + """Raise a Hermite series to a power. + + Returns the Hermite series `cs` raised to the power `pow`. The + arguement `cs` is a sequence of coefficients ordered from low to high. + i.e., [1,2,3] is the series ``P_0 + 2*P_1 + 3*P_2.`` + + Parameters + ---------- + cs : array_like + 1d array of Hermite series coefficients ordered from low to + high. + pow : integer + Power to which the series will be raised + maxpower : integer, optional + Maximum power allowed. This is mainly to limit growth of the series + to umanageable size. Default is 16 + + Returns + ------- + coef : ndarray + Hermite series of power. + + See Also + -------- + hermadd, hermsub, hermmul, hermdiv + + Examples + -------- + >>> from numpy.polynomial.hermite import hermpow + >>> hermpow([1, 2, 3], 2) + array([ 81., 52., 82., 12., 9.]) + + """ + # cs is a trimmed copy + [cs] = pu.as_series([cs]) + power = int(pow) + if power != pow or power < 0 : + raise ValueError("Power must be a non-negative integer.") + elif maxpower is not None and power > maxpower : + raise ValueError("Power is too large") + elif power == 0 : + return np.array([1], dtype=cs.dtype) + elif power == 1 : + return cs + else : + # This can be made more efficient by using powers of two + # in the usual way. + prd = cs + for i in range(2, power + 1) : + prd = hermmul(prd, cs) + return prd + + +def hermder(cs, m=1, scl=1) : + """ + Differentiate a Hermite series. + + Returns the series `cs` differentiated `m` times. At each iteration the + result is multiplied by `scl` (the scaling factor is for use in a linear + change of variable). The argument `cs` is the sequence of coefficients + from lowest order "term" to highest, e.g., [1,2,3] represents the series + ``P_0 + 2*P_1 + 3*P_2``. + + Parameters + ---------- + cs: array_like + 1-d array of Hermite series coefficients ordered from low to high. + m : int, optional + Number of derivatives taken, must be non-negative. (Default: 1) + scl : scalar, optional + Each differentiation is multiplied by `scl`. The end result is + multiplication by ``scl**m``. This is for use in a linear change of + variable. (Default: 1) + + Returns + ------- + der : ndarray + Hermite series of the derivative. + + See Also + -------- + hermint + + Notes + ----- + In general, the result of differentiating a Hermite series does not + resemble the same operation on a power series. Thus the result of this + function may be "un-intuitive," albeit correct; see Examples section + below. + + Examples + -------- + >>> from numpy.polynomial.hermite import hermder + >>> hermder([ 1. , 0.5, 0.5, 0.5]) + array([ 1., 2., 3.]) + >>> hermder([-0.5, 1./2., 1./8., 1./12., 1./16.], m=2) + array([ 1., 2., 3.]) + + """ + cnt = int(m) + + if cnt != m: + raise ValueError, "The order of derivation must be integer" + if cnt < 0 : + raise ValueError, "The order of derivation must be non-negative" + + # cs is a trimmed copy + [cs] = pu.as_series([cs]) + if cnt == 0: + return cs + elif cnt >= len(cs): + return cs[:1]*0 + else : + for i in range(cnt): + n = len(cs) - 1 + cs *= scl + der = np.empty(n, dtype=cs.dtype) + for j in range(n, 0, -1): + der[j - 1] = (2*j)*cs[j] + cs = der + return cs + + +def hermint(cs, m=1, k=[], lbnd=0, scl=1): + """ + Integrate a Hermite series. + + Returns a Hermite series that is the Hermite series `cs`, integrated + `m` times from `lbnd` to `x`. At each iteration the resulting series + is **multiplied** by `scl` and an integration constant, `k`, is added. + The scaling factor is for use in a linear change of variable. ("Buyer + beware": note that, depending on what one is doing, one may want `scl` + to be the reciprocal of what one might expect; for more information, + see the Notes section below.) The argument `cs` is a sequence of + coefficients, from lowest order Hermite series "term" to highest, + e.g., [1,2,3] represents the series :math:`P_0(x) + 2P_1(x) + 3P_2(x)`. + + Parameters + ---------- + cs : array_like + 1-d array of Hermite series coefficients, ordered from low to high. + m : int, optional + Order of integration, must be positive. (Default: 1) + k : {[], list, scalar}, optional + Integration constant(s). The value of the first integral at + ``lbnd`` is the first value in the list, the value of the second + integral at ``lbnd`` is the second value, etc. If ``k == []`` (the + default), all constants are set to zero. If ``m == 1``, a single + scalar can be given instead of a list. + lbnd : scalar, optional + The lower bound of the integral. (Default: 0) + scl : scalar, optional + Following each integration the result is *multiplied* by `scl` + before the integration constant is added. (Default: 1) + + Returns + ------- + S : ndarray + Hermite series coefficients of the integral. + + Raises + ------ + ValueError + If ``m < 0``, ``len(k) > m``, ``np.isscalar(lbnd) == False``, or + ``np.isscalar(scl) == False``. + + See Also + -------- + hermder + + Notes + ----- + Note that the result of each integration is *multiplied* by `scl`. + Why is this important to note? Say one is making a linear change of + variable :math:`u = ax + b` in an integral relative to `x`. Then + :math:`dx = du/a`, so one will need to set `scl` equal to :math:`1/a` + - perhaps not what one would have first thought. + + Also note that, in general, the result of integrating a C-series needs + to be "re-projected" onto the C-series basis set. Thus, typically, + the result of this function is "un-intuitive," albeit correct; see + Examples section below. + + Examples + -------- + >>> from numpy.polynomial.hermite import hermint + >>> hermint([1,2,3]) # integrate once, value 0 at 0. + array([ 1. , 0.5, 0.5, 0.5]) + >>> hermint([1,2,3], m=2) # integrate twice, value & deriv 0 at 0 + array([-0.5 , 0.5 , 0.125 , 0.08333333, 0.0625 ]) + >>> hermint([1,2,3], k=1) # integrate once, value 1 at 0. + array([ 2. , 0.5, 0.5, 0.5]) + >>> hermint([1,2,3], lbnd=-1) # integrate once, value 0 at -1 + array([-2. , 0.5, 0.5, 0.5]) + >>> hermint([1,2,3], m=2, k=[1,2], lbnd=-1) + array([ 1.66666667, -0.5 , 0.125 , 0.08333333, 0.0625 ]) + + """ + cnt = int(m) + if np.isscalar(k) : + k = [k] + + if cnt != m: + raise ValueError, "The order of integration must be integer" + if cnt < 0 : + raise ValueError, "The order of integration must be non-negative" + if len(k) > cnt : + raise ValueError, "Too many integration constants" + + # cs is a trimmed copy + [cs] = pu.as_series([cs]) + if cnt == 0: + return cs + + k = list(k) + [0]*(cnt - len(k)) + for i in range(cnt) : + n = len(cs) + cs *= scl + if n == 1 and cs[0] == 0: + cs[0] += k[i] + else: + tmp = np.empty(n + 1, dtype=cs.dtype) + tmp[0] = cs[0]*0 + tmp[1] = cs[0]/2 + for j in range(1, n): + tmp[j + 1] = cs[j]/(2*(j + 1)) + tmp[0] += k[i] - hermval(lbnd, tmp) + cs = tmp + return cs + + +def hermval(x, cs): + """Evaluate a Hermite series. + + If `cs` is of length `n`, this function returns : + + ``p(x) = cs[0]*P_0(x) + cs[1]*P_1(x) + ... + cs[n-1]*P_{n-1}(x)`` + + If x is a sequence or array then p(x) will have the same shape as x. + If r is a ring_like object that supports multiplication and addition + by the values in `cs`, then an object of the same type is returned. + + Parameters + ---------- + x : array_like, ring_like + Array of numbers or objects that support multiplication and + addition with themselves and with the elements of `cs`. + cs : array_like + 1-d array of Hermite coefficients ordered from low to high. + + Returns + ------- + values : ndarray, ring_like + If the return is an ndarray then it has the same shape as `x`. + + See Also + -------- + hermfit + + Examples + -------- + + Notes + ----- + The evaluation uses Clenshaw recursion, aka synthetic division. + + Examples + -------- + >>> from numpy.polynomial.hermite import hermval + >>> coef = [1,2,3] + >>> hermval(1, coef) + 11.0 + >>> hermval([[1,2],[3,4]], coef) + array([[ 11., 51.], + [ 115., 203.]]) + + """ + # cs is a trimmed copy + [cs] = pu.as_series([cs]) + if isinstance(x, tuple) or isinstance(x, list) : + x = np.asarray(x) + + x2 = x*2 + if len(cs) == 1 : + c0 = cs[0] + c1 = 0 + elif len(cs) == 2 : + c0 = cs[0] + c1 = cs[1] + else : + nd = len(cs) + c0 = cs[-2] + c1 = cs[-1] + for i in range(3, len(cs) + 1) : + tmp = c0 + nd = nd - 1 + c0 = cs[-i] - c1*(2*(nd - 1)) + c1 = tmp + c1*x2 + return c0 + c1*x2 + + +def hermvander(x, deg) : + """Vandermonde matrix of given degree. + + Returns the Vandermonde matrix of degree `deg` and sample points `x`. + This isn't a true Vandermonde matrix because `x` can be an arbitrary + ndarray and the Hermite polynomials aren't powers. If ``V`` is the + returned matrix and `x` is a 2d array, then the elements of ``V`` are + ``V[i,j,k] = P_k(x[i,j])``, where ``P_k`` is the Hermite polynomial + of degree ``k``. + + Parameters + ---------- + x : array_like + Array of points. The values are converted to double or complex + doubles. If x is scalar it is converted to a 1D array. + deg : integer + Degree of the resulting matrix. + + Returns + ------- + vander : Vandermonde matrix. + The shape of the returned matrix is ``x.shape + (deg+1,)``. The last + index is the degree. + + Examples + -------- + >>> from numpy.polynomial.hermite import hermvander + >>> x = np.array([-1, 0, 1]) + >>> hermvander(x, 3) + array([[ 1., -2., 2., 4.], + [ 1., 0., -2., -0.], + [ 1., 2., 2., -4.]]) + + """ + ideg = int(deg) + if ideg != deg: + raise ValueError("deg must be integer") + if ideg < 0: + raise ValueError("deg must be non-negative") + + x = np.array(x, copy=0, ndmin=1) + 0.0 + v = np.empty((ideg + 1,) + x.shape, dtype=x.dtype) + v[0] = x*0 + 1 + if ideg > 0 : + x2 = x*2 + v[1] = x2 + for i in range(2, ideg + 1) : + v[i] = (v[i-1]*x2 - v[i-2]*(2*(i - 1))) + return np.rollaxis(v, 0, v.ndim) + + +def hermfit(x, y, deg, rcond=None, full=False, w=None): + """ + Least squares fit of Hermite series to data. + + Fit a Hermite series ``p(x) = p[0] * P_{0}(x) + ... + p[deg] * + P_{deg}(x)`` of degree `deg` to points `(x, y)`. Returns a vector of + coefficients `p` that minimises the squared error. + + Parameters + ---------- + x : array_like, shape (M,) + x-coordinates of the M sample points ``(x[i], y[i])``. + y : array_like, shape (M,) or (M, K) + y-coordinates of the sample points. Several data sets of sample + points sharing the same x-coordinates can be fitted at once by + passing in a 2D-array that contains one dataset per column. + deg : int + Degree of the fitting polynomial + rcond : float, optional + Relative condition number of the fit. Singular values smaller than + this relative to the largest singular value will be ignored. The + default value is len(x)*eps, where eps is the relative precision of + the float type, about 2e-16 in most cases. + full : bool, optional + Switch determining nature of return value. When it is False (the + default) just the coefficients are returned, when True diagnostic + information from the singular value decomposition is also returned. + w : array_like, shape (`M`,), optional + Weights. If not None, the contribution of each point + ``(x[i],y[i])`` to the fit is weighted by `w[i]`. Ideally the + weights are chosen so that the errors of the products ``w[i]*y[i]`` + all have the same variance. The default value is None. + + Returns + ------- + coef : ndarray, shape (M,) or (M, K) + Hermite coefficients ordered from low to high. If `y` was 2-D, + the coefficients for the data in column k of `y` are in column + `k`. + + [residuals, rank, singular_values, rcond] : present when `full` = True + Residuals of the least-squares fit, the effective rank of the + scaled Vandermonde matrix and its singular values, and the + specified value of `rcond`. For more details, see `linalg.lstsq`. + + Warns + ----- + RankWarning + The rank of the coefficient matrix in the least-squares fit is + deficient. The warning is only raised if `full` = False. The + warnings can be turned off by + + >>> import warnings + >>> warnings.simplefilter('ignore', RankWarning) + + See Also + -------- + hermval : Evaluates a Hermite series. + hermvander : Vandermonde matrix of Hermite series. + polyfit : least squares fit using polynomials. + chebfit : least squares fit using Chebyshev series. + linalg.lstsq : Computes a least-squares fit from the matrix. + scipy.interpolate.UnivariateSpline : Computes spline fits. + + Notes + ----- + The solution are the coefficients ``c[i]`` of the Hermite series + ``P(x)`` that minimizes the squared error + + ``E = \\sum_j |y_j - P(x_j)|^2``. + + This problem is solved by setting up as the overdetermined matrix + equation + + ``V(x)*c = y``, + + where ``V`` is the Vandermonde matrix of `x`, the elements of ``c`` are + the coefficients to be solved for, and the elements of `y` are the + observed values. This equation is then solved using the singular value + decomposition of ``V``. + + If some of the singular values of ``V`` are so small that they are + neglected, then a `RankWarning` will be issued. This means that the + coeficient values may be poorly determined. Using a lower order fit + will usually get rid of the warning. The `rcond` parameter can also be + set to a value smaller than its default, but the resulting fit may be + spurious and have large contributions from roundoff error. + + Fits using Hermite series are usually better conditioned than fits + using power series, but much can depend on the distribution of the + sample points and the smoothness of the data. If the quality of the fit + is inadequate splines may be a good alternative. + + References + ---------- + .. [1] Wikipedia, "Curve fitting", + http://en.wikipedia.org/wiki/Curve_fitting + + Examples + -------- + >>> from numpy.polynomial.hermite import hermfit, hermval + >>> x = np.linspace(-10, 10) + >>> err = np.random.randn(len(x))/10 + >>> y = hermval(x, [1, 2, 3]) + err + >>> hermfit(x, y, 2) + array([ 0.97902637, 1.99849131, 3.00006 ]) + + """ + order = int(deg) + 1 + x = np.asarray(x) + 0.0 + y = np.asarray(y) + 0.0 + + # check arguments. + if deg < 0 : + raise ValueError, "expected deg >= 0" + if x.ndim != 1: + raise TypeError, "expected 1D vector for x" + if x.size == 0: + raise TypeError, "expected non-empty vector for x" + if y.ndim < 1 or y.ndim > 2 : + raise TypeError, "expected 1D or 2D array for y" + if len(x) != len(y): + raise TypeError, "expected x and y to have same length" + + # set up the least squares matrices + lhs = hermvander(x, deg) + rhs = y + if w is not None: + w = np.asarray(w) + 0.0 + if w.ndim != 1: + raise TypeError, "expected 1D vector for w" + if len(x) != len(w): + raise TypeError, "expected x and w to have same length" + # apply weights + if rhs.ndim == 2: + lhs *= w[:, np.newaxis] + rhs *= w[:, np.newaxis] + else: + lhs *= w[:, np.newaxis] + rhs *= w + + # set rcond + if rcond is None : + rcond = len(x)*np.finfo(x.dtype).eps + + # scale the design matrix and solve the least squares equation + scl = np.sqrt((lhs*lhs).sum(0)) + c, resids, rank, s = la.lstsq(lhs/scl, rhs, rcond) + c = (c.T/scl).T + + # warn on rank reduction + if rank != order and not full: + msg = "The fit may be poorly conditioned" + warnings.warn(msg, pu.RankWarning) + + if full : + return c, [resids, rank, s, rcond] + else : + return c + + +def hermroots(cs): + """ + Compute the roots of a Hermite series. + + Return the roots (a.k.a "zeros") of the Hermite series represented by + `cs`, which is the sequence of coefficients from lowest order "term" + to highest, e.g., [1,2,3] is the series ``L_0 + 2*L_1 + 3*L_2``. + + Parameters + ---------- + cs : array_like + 1-d array of Hermite series coefficients ordered from low to high. + + Returns + ------- + out : ndarray + Array of the roots. If all the roots are real, then so is the + dtype of ``out``; otherwise, ``out``'s dtype is complex. + + See Also + -------- + polyroots + chebroots + + Notes + ----- + Algorithm(s) used: + + Remember: because the Hermite series basis set is different from the + "standard" basis set, the results of this function *may* not be what + one is expecting. + + Examples + -------- + >>> from numpy.polynomial.hermite import hermroots, hermfromroots + >>> coef = hermfromroots([-1, 0, 1]) + >>> coef + array([ 0. , 0.25 , 0. , 0.125]) + >>> hermroots(coef) + array([ -1.00000000e+00, -1.38777878e-17, 1.00000000e+00]) + + """ + # cs is a trimmed copy + [cs] = pu.as_series([cs]) + if len(cs) <= 1 : + return np.array([], dtype=cs.dtype) + if len(cs) == 2 : + return np.array([-.5*cs[0]/cs[1]]) + + n = len(cs) - 1 + cs /= cs[-1] + cmat = np.zeros((n,n), dtype=cs.dtype) + cmat[1, 0] = .5 + for i in range(1, n): + cmat[i - 1, i] = i + if i != n - 1: + cmat[i + 1, i] = .5 + else: + cmat[:, i] -= cs[:-1]*.5 + roots = la.eigvals(cmat) + roots.sort() + return roots + + +# +# Hermite series class +# + +exec polytemplate.substitute(name='Hermite', nick='herm', domain='[-1,1]') diff --git a/numpy/polynomial/hermite_e.py b/numpy/polynomial/hermite_e.py new file mode 100644 index 000000000..e644e345a --- /dev/null +++ b/numpy/polynomial/hermite_e.py @@ -0,0 +1,1143 @@ +""" +Objects for dealing with Hermite series. + +This module provides a number of objects (mostly functions) useful for +dealing with Hermite series, including a `Hermite` class that +encapsulates the usual arithmetic operations. (General information +on how this module represents and works with such polynomials is in the +docstring for its "parent" sub-package, `numpy.polynomial`). + +Constants +--------- +- `hermedomain` -- Hermite series default domain, [-1,1]. +- `hermezero` -- Hermite series that evaluates identically to 0. +- `hermeone` -- Hermite series that evaluates identically to 1. +- `hermex` -- Hermite series for the identity map, ``f(x) = x``. + +Arithmetic +---------- +- `hermemulx` -- multiply a Hermite series in ``P_i(x)`` by ``x``. +- `hermeadd` -- add two Hermite series. +- `hermesub` -- subtract one Hermite series from another. +- `hermemul` -- multiply two Hermite series. +- `hermediv` -- divide one Hermite series by another. +- `hermeval` -- evaluate a Hermite series at given points. + +Calculus +-------- +- `hermeder` -- differentiate a Hermite series. +- `hermeint` -- integrate a Hermite series. + +Misc Functions +-------------- +- `hermefromroots` -- create a Hermite series with specified roots. +- `hermeroots` -- find the roots of a Hermite series. +- `hermevander` -- Vandermonde-like matrix for Hermite polynomials. +- `hermefit` -- least-squares fit returning a Hermite series. +- `hermetrim` -- trim leading coefficients from a Hermite series. +- `hermeline` -- Hermite series of given straight line. +- `herme2poly` -- convert a Hermite series to a polynomial. +- `poly2herme` -- convert a polynomial to a Hermite series. + +Classes +------- +- `Hermite` -- A Hermite series class. + +See also +-------- +`numpy.polynomial` + +""" +from __future__ import division + +import numpy as np +import numpy.linalg as la +import polyutils as pu +import warnings +from polytemplate import polytemplate + +__all__ = ['hermezero', 'hermeone', 'hermex', 'hermedomain', 'hermeline', + 'hermeadd', 'hermesub', 'hermemulx', 'hermemul', 'hermediv', 'hermeval', + 'hermeder', 'hermeint', 'herme2poly', 'poly2herme', 'hermefromroots', + 'hermevander', 'hermefit', 'hermetrim', 'hermeroots', 'HermiteE'] + +hermetrim = pu.trimcoef + +def poly2herme(pol) : + """ + poly2herme(pol) + + Convert a polynomial to a Hermite series. + + Convert an array representing the coefficients of a polynomial (relative + to the "standard" basis) ordered from lowest degree to highest, to an + array of the coefficients of the equivalent Hermite series, ordered + from lowest to highest degree. + + Parameters + ---------- + pol : array_like + 1-d array containing the polynomial coefficients + + Returns + ------- + cs : ndarray + 1-d array containing the coefficients of the equivalent Hermite + series. + + See Also + -------- + herme2poly + + Notes + ----- + The easy way to do conversions between polynomial basis sets + is to use the convert method of a class instance. + + Examples + -------- + >>> from numpy.polynomial.hermite_e import poly2herme + >>> poly2herme(np.arange(4)) + array([ 2., 10., 2., 3.]) + + """ + [pol] = pu.as_series([pol]) + deg = len(pol) - 1 + res = 0 + for i in range(deg, -1, -1) : + res = hermeadd(hermemulx(res), pol[i]) + return res + + +def herme2poly(cs) : + """ + Convert a Hermite series to a polynomial. + + Convert an array representing the coefficients of a Hermite series, + ordered from lowest degree to highest, to an array of the coefficients + of the equivalent polynomial (relative to the "standard" basis) ordered + from lowest to highest degree. + + Parameters + ---------- + cs : array_like + 1-d array containing the Hermite series coefficients, ordered + from lowest order term to highest. + + Returns + ------- + pol : ndarray + 1-d array containing the coefficients of the equivalent polynomial + (relative to the "standard" basis) ordered from lowest order term + to highest. + + See Also + -------- + poly2herme + + Notes + ----- + The easy way to do conversions between polynomial basis sets + is to use the convert method of a class instance. + + Examples + -------- + >>> from numpy.polynomial.hermite_e import herme2poly + >>> herme2poly([ 2., 10., 2., 3.]) + array([ 0., 1., 2., 3.]) + + """ + from polynomial import polyadd, polysub, polymulx + + [cs] = pu.as_series([cs]) + n = len(cs) + if n == 1: + return cs + if n == 2: + return cs + else: + c0 = cs[-2] + c1 = cs[-1] + # i is the current degree of c1 + for i in range(n - 1, 1, -1) : + tmp = c0 + c0 = polysub(cs[i - 2], c1*(i - 1)) + c1 = polyadd(tmp, polymulx(c1)) + return polyadd(c0, polymulx(c1)) + +# +# These are constant arrays are of integer type so as to be compatible +# with the widest range of other types, such as Decimal. +# + +# Hermite +hermedomain = np.array([-1,1]) + +# Hermite coefficients representing zero. +hermezero = np.array([0]) + +# Hermite coefficients representing one. +hermeone = np.array([1]) + +# Hermite coefficients representing the identity x. +hermex = np.array([0, 1]) + + +def hermeline(off, scl) : + """ + Hermite series whose graph is a straight line. + + + + Parameters + ---------- + off, scl : scalars + The specified line is given by ``off + scl*x``. + + Returns + ------- + y : ndarray + This module's representation of the Hermite series for + ``off + scl*x``. + + See Also + -------- + polyline, chebline + + Examples + -------- + >>> from numpy.polynomial.hermite_e import hermeline + >>> from numpy.polynomial.hermite_e import hermeline, hermeval + >>> hermeval(0,hermeline(3, 2)) + 3.0 + >>> hermeval(1,hermeline(3, 2)) + 5.0 + + """ + if scl != 0 : + return np.array([off,scl]) + else : + return np.array([off]) + + +def hermefromroots(roots) : + """ + Generate a Hermite series with the given roots. + + Return the array of coefficients for the P-series whose roots (a.k.a. + "zeros") are given by *roots*. The returned array of coefficients is + ordered from lowest order "term" to highest, and zeros of multiplicity + greater than one must be included in *roots* a number of times equal + to their multiplicity (e.g., if `2` is a root of multiplicity three, + then [2,2,2] must be in *roots*). + + Parameters + ---------- + roots : array_like + Sequence containing the roots. + + Returns + ------- + out : ndarray + 1-d array of the Hermite series coefficients, ordered from low to + high. If all roots are real, ``out.dtype`` is a float type; + otherwise, ``out.dtype`` is a complex type, even if all the + coefficients in the result are real (see Examples below). + + See Also + -------- + polyfromroots, chebfromroots + + Notes + ----- + What is returned are the :math:`c_i` such that: + + .. math:: + + \\sum_{i=0}^{n} c_i*P_i(x) = \\prod_{i=0}^{n} (x - roots[i]) + + where ``n == len(roots)`` and :math:`P_i(x)` is the `i`-th Hermite + (basis) polynomial over the domain `[-1,1]`. Note that, unlike + `polyfromroots`, due to the nature of the Hermite basis set, the + above identity *does not* imply :math:`c_n = 1` identically (see + Examples). + + Examples + -------- + >>> from numpy.polynomial.hermite_e import hermefromroots, hermeval + >>> coef = hermefromroots((-1, 0, 1)) + >>> hermeval((-1, 0, 1), coef) + array([ 0., 0., 0.]) + >>> coef = hermefromroots((-1j, 1j)) + >>> hermeval((-1j, 1j), coef) + array([ 0.+0.j, 0.+0.j]) + + """ + if len(roots) == 0 : + return np.ones(1) + else : + [roots] = pu.as_series([roots], trim=False) + prd = np.array([1], dtype=roots.dtype) + for r in roots: + prd = hermesub(hermemulx(prd), r*prd) + return prd + + +def hermeadd(c1, c2): + """ + Add one Hermite series to another. + + Returns the sum of two Hermite series `c1` + `c2`. The arguments + are sequences of coefficients ordered from lowest order term to + highest, i.e., [1,2,3] represents the series ``P_0 + 2*P_1 + 3*P_2``. + + Parameters + ---------- + c1, c2 : array_like + 1-d arrays of Hermite series coefficients ordered from low to + high. + + Returns + ------- + out : ndarray + Array representing the Hermite series of their sum. + + See Also + -------- + hermesub, hermemul, hermediv, hermepow + + Notes + ----- + Unlike multiplication, division, etc., the sum of two Hermite series + is a Hermite series (without having to "reproject" the result onto + the basis set) so addition, just like that of "standard" polynomials, + is simply "component-wise." + + Examples + -------- + >>> from numpy.polynomial.hermite_e import hermeadd + >>> hermeadd([1, 2, 3], [1, 2, 3, 4]) + array([ 2., 4., 6., 4.]) + + """ + # c1, c2 are trimmed copies + [c1, c2] = pu.as_series([c1, c2]) + if len(c1) > len(c2) : + c1[:c2.size] += c2 + ret = c1 + else : + c2[:c1.size] += c1 + ret = c2 + return pu.trimseq(ret) + + +def hermesub(c1, c2): + """ + Subtract one Hermite series from another. + + Returns the difference of two Hermite series `c1` - `c2`. The + sequences of coefficients are from lowest order term to highest, i.e., + [1,2,3] represents the series ``P_0 + 2*P_1 + 3*P_2``. + + Parameters + ---------- + c1, c2 : array_like + 1-d arrays of Hermite series coefficients ordered from low to + high. + + Returns + ------- + out : ndarray + Of Hermite series coefficients representing their difference. + + See Also + -------- + hermeadd, hermemul, hermediv, hermepow + + Notes + ----- + Unlike multiplication, division, etc., the difference of two Hermite + series is a Hermite series (without having to "reproject" the result + onto the basis set) so subtraction, just like that of "standard" + polynomials, is simply "component-wise." + + Examples + -------- + >>> from numpy.polynomial.hermite_e import hermesub + >>> hermesub([1, 2, 3, 4], [1, 2, 3]) + array([ 0., 0., 0., 4.]) + + """ + # c1, c2 are trimmed copies + [c1, c2] = pu.as_series([c1, c2]) + if len(c1) > len(c2) : + c1[:c2.size] -= c2 + ret = c1 + else : + c2 = -c2 + c2[:c1.size] += c1 + ret = c2 + return pu.trimseq(ret) + + +def hermemulx(cs): + """Multiply a Hermite series by x. + + Multiply the Hermite series `cs` by x, where x is the independent + variable. + + + Parameters + ---------- + cs : array_like + 1-d array of Hermite series coefficients ordered from low to + high. + + Returns + ------- + out : ndarray + Array representing the result of the multiplication. + + Notes + ----- + The multiplication uses the recursion relationship for Hermite + polynomials in the form + + .. math:: + + xP_i(x) = (P_{i + 1}(x) + iP_{i - 1}(x))) + + Examples + -------- + >>> from numpy.polynomial.hermite_e import hermemulx + >>> hermemulx([1, 2, 3]) + array([ 2., 7., 2., 3.]) + + """ + # cs is a trimmed copy + [cs] = pu.as_series([cs]) + # The zero series needs special treatment + if len(cs) == 1 and cs[0] == 0: + return cs + + prd = np.empty(len(cs) + 1, dtype=cs.dtype) + prd[0] = cs[0]*0 + prd[1] = cs[0] + for i in range(1, len(cs)): + prd[i + 1] = cs[i] + prd[i - 1] += cs[i]*i + return prd + + +def hermemul(c1, c2): + """ + Multiply one Hermite series by another. + + Returns the product of two Hermite series `c1` * `c2`. The arguments + are sequences of coefficients, from lowest order "term" to highest, + e.g., [1,2,3] represents the series ``P_0 + 2*P_1 + 3*P_2``. + + Parameters + ---------- + c1, c2 : array_like + 1-d arrays of Hermite series coefficients ordered from low to + high. + + Returns + ------- + out : ndarray + Of Hermite series coefficients representing their product. + + See Also + -------- + hermeadd, hermesub, hermediv, hermepow + + Notes + ----- + In general, the (polynomial) product of two C-series results in terms + that are not in the Hermite polynomial basis set. Thus, to express + the product as a Hermite series, it is necessary to "re-project" the + product onto said basis set, which may produce "un-intuitive" (but + correct) results; see Examples section below. + + Examples + -------- + >>> from numpy.polynomial.hermite_e import hermemul + >>> hermemul([1, 2, 3], [0, 1, 2]) + array([ 14., 15., 28., 7., 6.]) + + """ + # s1, s2 are trimmed copies + [c1, c2] = pu.as_series([c1, c2]) + + if len(c1) > len(c2): + cs = c2 + xs = c1 + else: + cs = c1 + xs = c2 + + if len(cs) == 1: + c0 = cs[0]*xs + c1 = 0 + elif len(cs) == 2: + c0 = cs[0]*xs + c1 = cs[1]*xs + else : + nd = len(cs) + c0 = cs[-2]*xs + c1 = cs[-1]*xs + for i in range(3, len(cs) + 1) : + tmp = c0 + nd = nd - 1 + c0 = hermesub(cs[-i]*xs, c1*(nd - 1)) + c1 = hermeadd(tmp, hermemulx(c1)) + return hermeadd(c0, hermemulx(c1)) + + +def hermediv(c1, c2): + """ + Divide one Hermite series by another. + + Returns the quotient-with-remainder of two Hermite series + `c1` / `c2`. The arguments are sequences of coefficients from lowest + order "term" to highest, e.g., [1,2,3] represents the series + ``P_0 + 2*P_1 + 3*P_2``. + + Parameters + ---------- + c1, c2 : array_like + 1-d arrays of Hermite series coefficients ordered from low to + high. + + Returns + ------- + [quo, rem] : ndarrays + Of Hermite series coefficients representing the quotient and + remainder. + + See Also + -------- + hermeadd, hermesub, hermemul, hermepow + + Notes + ----- + In general, the (polynomial) division of one Hermite series by another + results in quotient and remainder terms that are not in the Hermite + polynomial basis set. Thus, to express these results as a Hermite + series, it is necessary to "re-project" the results onto the Hermite + basis set, which may produce "un-intuitive" (but correct) results; see + Examples section below. + + Examples + -------- + >>> from numpy.polynomial.hermite_e import hermediv + >>> hermediv([ 14., 15., 28., 7., 6.], [0, 1, 2]) + (array([ 1., 2., 3.]), array([ 0.])) + >>> hermediv([ 15., 17., 28., 7., 6.], [0, 1, 2]) + (array([ 1., 2., 3.]), array([ 1., 2.])) + + """ + # c1, c2 are trimmed copies + [c1, c2] = pu.as_series([c1, c2]) + if c2[-1] == 0 : + raise ZeroDivisionError() + + lc1 = len(c1) + lc2 = len(c2) + if lc1 < lc2 : + return c1[:1]*0, c1 + elif lc2 == 1 : + return c1/c2[-1], c1[:1]*0 + else : + quo = np.empty(lc1 - lc2 + 1, dtype=c1.dtype) + rem = c1 + for i in range(lc1 - lc2, - 1, -1): + p = hermemul([0]*i + [1], c2) + q = rem[-1]/p[-1] + rem = rem[:-1] - q*p[:-1] + quo[i] = q + return quo, pu.trimseq(rem) + + +def hermepow(cs, pow, maxpower=16) : + """Raise a Hermite series to a power. + + Returns the Hermite series `cs` raised to the power `pow`. The + arguement `cs` is a sequence of coefficients ordered from low to high. + i.e., [1,2,3] is the series ``P_0 + 2*P_1 + 3*P_2.`` + + Parameters + ---------- + cs : array_like + 1d array of Hermite series coefficients ordered from low to + high. + pow : integer + Power to which the series will be raised + maxpower : integer, optional + Maximum power allowed. This is mainly to limit growth of the series + to umanageable size. Default is 16 + + Returns + ------- + coef : ndarray + Hermite series of power. + + See Also + -------- + hermeadd, hermesub, hermemul, hermediv + + Examples + -------- + >>> from numpy.polynomial.hermite_e import hermepow + >>> hermepow([1, 2, 3], 2) + array([ 23., 28., 46., 12., 9.]) + + """ + # cs is a trimmed copy + [cs] = pu.as_series([cs]) + power = int(pow) + if power != pow or power < 0 : + raise ValueError("Power must be a non-negative integer.") + elif maxpower is not None and power > maxpower : + raise ValueError("Power is too large") + elif power == 0 : + return np.array([1], dtype=cs.dtype) + elif power == 1 : + return cs + else : + # This can be made more efficient by using powers of two + # in the usual way. + prd = cs + for i in range(2, power + 1) : + prd = hermemul(prd, cs) + return prd + + +def hermeder(cs, m=1, scl=1) : + """ + Differentiate a Hermite series. + + Returns the series `cs` differentiated `m` times. At each iteration the + result is multiplied by `scl` (the scaling factor is for use in a linear + change of variable). The argument `cs` is the sequence of coefficients + from lowest order "term" to highest, e.g., [1,2,3] represents the series + ``P_0 + 2*P_1 + 3*P_2``. + + Parameters + ---------- + cs: array_like + 1-d array of Hermite series coefficients ordered from low to high. + m : int, optional + Number of derivatives taken, must be non-negative. (Default: 1) + scl : scalar, optional + Each differentiation is multiplied by `scl`. The end result is + multiplication by ``scl**m``. This is for use in a linear change of + variable. (Default: 1) + + Returns + ------- + der : ndarray + Hermite series of the derivative. + + See Also + -------- + hermeint + + Notes + ----- + In general, the result of differentiating a Hermite series does not + resemble the same operation on a power series. Thus the result of this + function may be "un-intuitive," albeit correct; see Examples section + below. + + Examples + -------- + >>> from numpy.polynomial.hermite_e import hermeder + >>> hermeder([ 1., 1., 1., 1.]) + array([ 1., 2., 3.]) + >>> hermeder([-0.25, 1., 1./2., 1./3., 1./4 ], m=2) + array([ 1., 2., 3.]) + + """ + cnt = int(m) + + if cnt != m: + raise ValueError, "The order of derivation must be integer" + if cnt < 0 : + raise ValueError, "The order of derivation must be non-negative" + + # cs is a trimmed copy + [cs] = pu.as_series([cs]) + if cnt == 0: + return cs + elif cnt >= len(cs): + return cs[:1]*0 + else : + for i in range(cnt): + n = len(cs) - 1 + cs *= scl + der = np.empty(n, dtype=cs.dtype) + for j in range(n, 0, -1): + der[j - 1] = j*cs[j] + cs = der + return cs + + +def hermeint(cs, m=1, k=[], lbnd=0, scl=1): + """ + Integrate a Hermite series. + + Returns a Hermite series that is the Hermite series `cs`, integrated + `m` times from `lbnd` to `x`. At each iteration the resulting series + is **multiplied** by `scl` and an integration constant, `k`, is added. + The scaling factor is for use in a linear change of variable. ("Buyer + beware": note that, depending on what one is doing, one may want `scl` + to be the reciprocal of what one might expect; for more information, + see the Notes section below.) The argument `cs` is a sequence of + coefficients, from lowest order Hermite series "term" to highest, + e.g., [1,2,3] represents the series :math:`P_0(x) + 2P_1(x) + 3P_2(x)`. + + Parameters + ---------- + cs : array_like + 1-d array of Hermite series coefficients, ordered from low to high. + m : int, optional + Order of integration, must be positive. (Default: 1) + k : {[], list, scalar}, optional + Integration constant(s). The value of the first integral at + ``lbnd`` is the first value in the list, the value of the second + integral at ``lbnd`` is the second value, etc. If ``k == []`` (the + default), all constants are set to zero. If ``m == 1``, a single + scalar can be given instead of a list. + lbnd : scalar, optional + The lower bound of the integral. (Default: 0) + scl : scalar, optional + Following each integration the result is *multiplied* by `scl` + before the integration constant is added. (Default: 1) + + Returns + ------- + S : ndarray + Hermite series coefficients of the integral. + + Raises + ------ + ValueError + If ``m < 0``, ``len(k) > m``, ``np.isscalar(lbnd) == False``, or + ``np.isscalar(scl) == False``. + + See Also + -------- + hermeder + + Notes + ----- + Note that the result of each integration is *multiplied* by `scl`. + Why is this important to note? Say one is making a linear change of + variable :math:`u = ax + b` in an integral relative to `x`. Then + :math:`dx = du/a`, so one will need to set `scl` equal to :math:`1/a` + - perhaps not what one would have first thought. + + Also note that, in general, the result of integrating a C-series needs + to be "re-projected" onto the C-series basis set. Thus, typically, + the result of this function is "un-intuitive," albeit correct; see + Examples section below. + + Examples + -------- + >>> from numpy.polynomial.hermite_e import hermeint + >>> hermeint([1, 2, 3]) # integrate once, value 0 at 0. + array([ 1., 1., 1., 1.]) + >>> hermeint([1, 2, 3], m=2) # integrate twice, value & deriv 0 at 0 + array([-0.25 , 1. , 0.5 , 0.33333333, 0.25 ]) + >>> hermeint([1, 2, 3], k=1) # integrate once, value 1 at 0. + array([ 2., 1., 1., 1.]) + >>> hermeint([1, 2, 3], lbnd=-1) # integrate once, value 0 at -1 + array([-1., 1., 1., 1.]) + >>> hermeint([1, 2, 3], m=2, k=[1,2], lbnd=-1) + array([ 1.83333333, 0. , 0.5 , 0.33333333, 0.25 ]) + + """ + cnt = int(m) + if np.isscalar(k) : + k = [k] + + if cnt != m: + raise ValueError, "The order of integration must be integer" + if cnt < 0 : + raise ValueError, "The order of integration must be non-negative" + if len(k) > cnt : + raise ValueError, "Too many integration constants" + + # cs is a trimmed copy + [cs] = pu.as_series([cs]) + if cnt == 0: + return cs + + k = list(k) + [0]*(cnt - len(k)) + for i in range(cnt) : + n = len(cs) + cs *= scl + if n == 1 and cs[0] == 0: + cs[0] += k[i] + else: + tmp = np.empty(n + 1, dtype=cs.dtype) + tmp[0] = cs[0]*0 + tmp[1] = cs[0] + for j in range(1, n): + tmp[j + 1] = cs[j]/(j + 1) + tmp[0] += k[i] - hermeval(lbnd, tmp) + cs = tmp + return cs + + +def hermeval(x, cs): + """Evaluate a Hermite series. + + If `cs` is of length `n`, this function returns : + + ``p(x) = cs[0]*P_0(x) + cs[1]*P_1(x) + ... + cs[n-1]*P_{n-1}(x)`` + + If x is a sequence or array then p(x) will have the same shape as x. + If r is a ring_like object that supports multiplication and addition + by the values in `cs`, then an object of the same type is returned. + + Parameters + ---------- + x : array_like, ring_like + Array of numbers or objects that support multiplication and + addition with themselves and with the elements of `cs`. + cs : array_like + 1-d array of Hermite coefficients ordered from low to high. + + Returns + ------- + values : ndarray, ring_like + If the return is an ndarray then it has the same shape as `x`. + + See Also + -------- + hermefit + + Examples + -------- + + Notes + ----- + The evaluation uses Clenshaw recursion, aka synthetic division. + + Examples + -------- + >>> from numpy.polynomial.hermite_e import hermeval + >>> coef = [1,2,3] + >>> hermeval(1, coef) + 3.0 + >>> hermeval([[1,2],[3,4]], coef) + array([[ 3., 14.], + [ 31., 54.]]) + + """ + # cs is a trimmed copy + [cs] = pu.as_series([cs]) + if isinstance(x, tuple) or isinstance(x, list) : + x = np.asarray(x) + + if len(cs) == 1 : + c0 = cs[0] + c1 = 0 + elif len(cs) == 2 : + c0 = cs[0] + c1 = cs[1] + else : + nd = len(cs) + c0 = cs[-2] + c1 = cs[-1] + for i in range(3, len(cs) + 1) : + tmp = c0 + nd = nd - 1 + c0 = cs[-i] - c1*(nd - 1) + c1 = tmp + c1*x + return c0 + c1*x + + +def hermevander(x, deg) : + """Vandermonde matrix of given degree. + + Returns the Vandermonde matrix of degree `deg` and sample points `x`. + This isn't a true Vandermonde matrix because `x` can be an arbitrary + ndarray and the Hermite polynomials aren't powers. If ``V`` is the + returned matrix and `x` is a 2d array, then the elements of ``V`` are + ``V[i,j,k] = P_k(x[i,j])``, where ``P_k`` is the Hermite polynomial + of degree ``k``. + + Parameters + ---------- + x : array_like + Array of points. The values are converted to double or complex + doubles. If x is scalar it is converted to a 1D array. + deg : integer + Degree of the resulting matrix. + + Returns + ------- + vander : Vandermonde matrix. + The shape of the returned matrix is ``x.shape + (deg+1,)``. The last + index is the degree. + + Examples + -------- + >>> from numpy.polynomial.hermite_e import hermevander + >>> x = np.array([-1, 0, 1]) + >>> hermevander(x, 3) + array([[ 1., -1., 0., 2.], + [ 1., 0., -1., -0.], + [ 1., 1., 0., -2.]]) + + """ + ideg = int(deg) + if ideg != deg: + raise ValueError("deg must be integer") + if ideg < 0: + raise ValueError("deg must be non-negative") + + x = np.array(x, copy=0, ndmin=1) + 0.0 + v = np.empty((ideg + 1,) + x.shape, dtype=x.dtype) + v[0] = x*0 + 1 + if ideg > 0 : + v[1] = x + for i in range(2, ideg + 1) : + v[i] = (v[i-1]*x - v[i-2]*(i - 1)) + return np.rollaxis(v, 0, v.ndim) + + +def hermefit(x, y, deg, rcond=None, full=False, w=None): + """ + Least squares fit of Hermite series to data. + + Fit a Hermite series ``p(x) = p[0] * P_{0}(x) + ... + p[deg] * + P_{deg}(x)`` of degree `deg` to points `(x, y)`. Returns a vector of + coefficients `p` that minimises the squared error. + + Parameters + ---------- + x : array_like, shape (M,) + x-coordinates of the M sample points ``(x[i], y[i])``. + y : array_like, shape (M,) or (M, K) + y-coordinates of the sample points. Several data sets of sample + points sharing the same x-coordinates can be fitted at once by + passing in a 2D-array that contains one dataset per column. + deg : int + Degree of the fitting polynomial + rcond : float, optional + Relative condition number of the fit. Singular values smaller than + this relative to the largest singular value will be ignored. The + default value is len(x)*eps, where eps is the relative precision of + the float type, about 2e-16 in most cases. + full : bool, optional + Switch determining nature of return value. When it is False (the + default) just the coefficients are returned, when True diagnostic + information from the singular value decomposition is also returned. + w : array_like, shape (`M`,), optional + Weights. If not None, the contribution of each point + ``(x[i],y[i])`` to the fit is weighted by `w[i]`. Ideally the + weights are chosen so that the errors of the products ``w[i]*y[i]`` + all have the same variance. The default value is None. + + Returns + ------- + coef : ndarray, shape (M,) or (M, K) + Hermite coefficients ordered from low to high. If `y` was 2-D, + the coefficients for the data in column k of `y` are in column + `k`. + + [residuals, rank, singular_values, rcond] : present when `full` = True + Residuals of the least-squares fit, the effective rank of the + scaled Vandermonde matrix and its singular values, and the + specified value of `rcond`. For more details, see `linalg.lstsq`. + + Warns + ----- + RankWarning + The rank of the coefficient matrix in the least-squares fit is + deficient. The warning is only raised if `full` = False. The + warnings can be turned off by + + >>> import warnings + >>> warnings.simplefilter('ignore', RankWarning) + + See Also + -------- + hermeval : Evaluates a Hermite series. + hermevander : Vandermonde matrix of Hermite series. + polyfit : least squares fit using polynomials. + chebfit : least squares fit using Chebyshev series. + linalg.lstsq : Computes a least-squares fit from the matrix. + scipy.interpolate.UnivariateSpline : Computes spline fits. + + Notes + ----- + The solution are the coefficients ``c[i]`` of the Hermite series + ``P(x)`` that minimizes the squared error + + ``E = \\sum_j |y_j - P(x_j)|^2``. + + This problem is solved by setting up as the overdetermined matrix + equation + + ``V(x)*c = y``, + + where ``V`` is the Vandermonde matrix of `x`, the elements of ``c`` are + the coefficients to be solved for, and the elements of `y` are the + observed values. This equation is then solved using the singular value + decomposition of ``V``. + + If some of the singular values of ``V`` are so small that they are + neglected, then a `RankWarning` will be issued. This means that the + coeficient values may be poorly determined. Using a lower order fit + will usually get rid of the warning. The `rcond` parameter can also be + set to a value smaller than its default, but the resulting fit may be + spurious and have large contributions from roundoff error. + + Fits using Hermite series are usually better conditioned than fits + using power series, but much can depend on the distribution of the + sample points and the smoothness of the data. If the quality of the fit + is inadequate splines may be a good alternative. + + References + ---------- + .. [1] Wikipedia, "Curve fitting", + http://en.wikipedia.org/wiki/Curve_fitting + + Examples + -------- + >>> from numpy.polynomial.hermite_e import hermefit, hermeval + >>> x = np.linspace(-10, 10) + >>> err = np.random.randn(len(x))/10 + >>> y = hermeval(x, [1, 2, 3]) + err + >>> hermefit(x, y, 2) + array([ 1.01690445, 1.99951418, 2.99948696]) + + """ + order = int(deg) + 1 + x = np.asarray(x) + 0.0 + y = np.asarray(y) + 0.0 + + # check arguments. + if deg < 0 : + raise ValueError, "expected deg >= 0" + if x.ndim != 1: + raise TypeError, "expected 1D vector for x" + if x.size == 0: + raise TypeError, "expected non-empty vector for x" + if y.ndim < 1 or y.ndim > 2 : + raise TypeError, "expected 1D or 2D array for y" + if len(x) != len(y): + raise TypeError, "expected x and y to have same length" + + # set up the least squares matrices + lhs = hermevander(x, deg) + rhs = y + if w is not None: + w = np.asarray(w) + 0.0 + if w.ndim != 1: + raise TypeError, "expected 1D vector for w" + if len(x) != len(w): + raise TypeError, "expected x and w to have same length" + # apply weights + if rhs.ndim == 2: + lhs *= w[:, np.newaxis] + rhs *= w[:, np.newaxis] + else: + lhs *= w[:, np.newaxis] + rhs *= w + + # set rcond + if rcond is None : + rcond = len(x)*np.finfo(x.dtype).eps + + # scale the design matrix and solve the least squares equation + scl = np.sqrt((lhs*lhs).sum(0)) + c, resids, rank, s = la.lstsq(lhs/scl, rhs, rcond) + c = (c.T/scl).T + + # warn on rank reduction + if rank != order and not full: + msg = "The fit may be poorly conditioned" + warnings.warn(msg, pu.RankWarning) + + if full : + return c, [resids, rank, s, rcond] + else : + return c + + +def hermeroots(cs): + """ + Compute the roots of a Hermite series. + + Return the roots (a.k.a "zeros") of the Hermite series represented by + `cs`, which is the sequence of coefficients from lowest order "term" + to highest, e.g., [1,2,3] is the series ``L_0 + 2*L_1 + 3*L_2``. + + Parameters + ---------- + cs : array_like + 1-d array of Hermite series coefficients ordered from low to high. + + Returns + ------- + out : ndarray + Array of the roots. If all the roots are real, then so is the + dtype of ``out``; otherwise, ``out``'s dtype is complex. + + See Also + -------- + polyroots + chebroots + + Notes + ----- + Algorithm(s) used: + + Remember: because the Hermite series basis set is different from the + "standard" basis set, the results of this function *may* not be what + one is expecting. + + Examples + -------- + >>> from numpy.polynomial.hermite_e import hermeroots, hermefromroots + >>> coef = hermefromroots([-1, 0, 1]) + >>> coef + array([ 0., 2., 0., 1.]) + >>> hermeroots(coef) + array([-1., 0., 1.]) + + """ + # cs is a trimmed copy + [cs] = pu.as_series([cs]) + if len(cs) <= 1 : + return np.array([], dtype=cs.dtype) + if len(cs) == 2 : + return np.array([-.5*cs[0]/cs[1]]) + + n = len(cs) - 1 + cs /= cs[-1] + cmat = np.zeros((n,n), dtype=cs.dtype) + cmat[1, 0] = 1 + for i in range(1, n): + cmat[i - 1, i] = i + if i != n - 1: + cmat[i + 1, i] = 1 + else: + cmat[:, i] -= cs[:-1] + roots = la.eigvals(cmat) + roots.sort() + return roots + + +# +# HermiteE series class +# + +exec polytemplate.substitute(name='HermiteE', nick='herme', domain='[-1,1]') diff --git a/numpy/polynomial/laguerre.py b/numpy/polynomial/laguerre.py new file mode 100644 index 000000000..b6389bf63 --- /dev/null +++ b/numpy/polynomial/laguerre.py @@ -0,0 +1,1146 @@ +""" +Objects for dealing with Laguerre series. + +This module provides a number of objects (mostly functions) useful for +dealing with Laguerre series, including a `Laguerre` class that +encapsulates the usual arithmetic operations. (General information +on how this module represents and works with such polynomials is in the +docstring for its "parent" sub-package, `numpy.polynomial`). + +Constants +--------- +- `lagdomain` -- Laguerre series default domain, [-1,1]. +- `lagzero` -- Laguerre series that evaluates identically to 0. +- `lagone` -- Laguerre series that evaluates identically to 1. +- `lagx` -- Laguerre series for the identity map, ``f(x) = x``. + +Arithmetic +---------- +- `lagmulx` -- multiply a Laguerre series in ``P_i(x)`` by ``x``. +- `lagadd` -- add two Laguerre series. +- `lagsub` -- subtract one Laguerre series from another. +- `lagmul` -- multiply two Laguerre series. +- `lagdiv` -- divide one Laguerre series by another. +- `lagval` -- evaluate a Laguerre series at given points. + +Calculus +-------- +- `lagder` -- differentiate a Laguerre series. +- `lagint` -- integrate a Laguerre series. + +Misc Functions +-------------- +- `lagfromroots` -- create a Laguerre series with specified roots. +- `lagroots` -- find the roots of a Laguerre series. +- `lagvander` -- Vandermonde-like matrix for Laguerre polynomials. +- `lagfit` -- least-squares fit returning a Laguerre series. +- `lagtrim` -- trim leading coefficients from a Laguerre series. +- `lagline` -- Laguerre series of given straight line. +- `lag2poly` -- convert a Laguerre series to a polynomial. +- `poly2lag` -- convert a polynomial to a Laguerre series. + +Classes +------- +- `Laguerre` -- A Laguerre series class. + +See also +-------- +`numpy.polynomial` + +""" +from __future__ import division + +__all__ = ['lagzero', 'lagone', 'lagx', 'lagdomain', 'lagline', + 'lagadd', 'lagsub', 'lagmulx', 'lagmul', 'lagdiv', 'lagval', + 'lagder', 'lagint', 'lag2poly', 'poly2lag', 'lagfromroots', + 'lagvander', 'lagfit', 'lagtrim', 'lagroots', 'Laguerre'] + +import numpy as np +import numpy.linalg as la +import polyutils as pu +import warnings +from polytemplate import polytemplate + +lagtrim = pu.trimcoef + +def poly2lag(pol) : + """ + poly2lag(pol) + + Convert a polynomial to a Laguerre series. + + Convert an array representing the coefficients of a polynomial (relative + to the "standard" basis) ordered from lowest degree to highest, to an + array of the coefficients of the equivalent Laguerre series, ordered + from lowest to highest degree. + + Parameters + ---------- + pol : array_like + 1-d array containing the polynomial coefficients + + Returns + ------- + cs : ndarray + 1-d array containing the coefficients of the equivalent Laguerre + series. + + See Also + -------- + lag2poly + + Notes + ----- + The easy way to do conversions between polynomial basis sets + is to use the convert method of a class instance. + + Examples + -------- + >>> from numpy.polynomial.laguerre import poly2lag + >>> poly2lag(np.arange(4)) + array([ 23., -63., 58., -18.]) + + """ + [pol] = pu.as_series([pol]) + deg = len(pol) - 1 + res = 0 + for i in range(deg, -1, -1) : + res = lagadd(lagmulx(res), pol[i]) + return res + + +def lag2poly(cs) : + """ + Convert a Laguerre series to a polynomial. + + Convert an array representing the coefficients of a Laguerre series, + ordered from lowest degree to highest, to an array of the coefficients + of the equivalent polynomial (relative to the "standard" basis) ordered + from lowest to highest degree. + + Parameters + ---------- + cs : array_like + 1-d array containing the Laguerre series coefficients, ordered + from lowest order term to highest. + + Returns + ------- + pol : ndarray + 1-d array containing the coefficients of the equivalent polynomial + (relative to the "standard" basis) ordered from lowest order term + to highest. + + See Also + -------- + poly2lag + + Notes + ----- + The easy way to do conversions between polynomial basis sets + is to use the convert method of a class instance. + + Examples + -------- + >>> from numpy.polynomial.laguerre import lag2poly + >>> lag2poly([ 23., -63., 58., -18.]) + array([ 0., 1., 2., 3.]) + + """ + from polynomial import polyadd, polysub, polymulx + + [cs] = pu.as_series([cs]) + n = len(cs) + if n == 1: + return cs + else: + c0 = cs[-2] + c1 = cs[-1] + # i is the current degree of c1 + for i in range(n - 1, 1, -1): + tmp = c0 + c0 = polysub(cs[i - 2], (c1*(i - 1))/i) + c1 = polyadd(tmp, polysub((2*i - 1)*c1, polymulx(c1))/i) + return polyadd(c0, polysub(c1, polymulx(c1))) + +# +# These are constant arrays are of integer type so as to be compatible +# with the widest range of other types, such as Decimal. +# + +# Laguerre +lagdomain = np.array([0,1]) + +# Laguerre coefficients representing zero. +lagzero = np.array([0]) + +# Laguerre coefficients representing one. +lagone = np.array([1]) + +# Laguerre coefficients representing the identity x. +lagx = np.array([1, -1]) + + +def lagline(off, scl) : + """ + Laguerre series whose graph is a straight line. + + + + Parameters + ---------- + off, scl : scalars + The specified line is given by ``off + scl*x``. + + Returns + ------- + y : ndarray + This module's representation of the Laguerre series for + ``off + scl*x``. + + See Also + -------- + polyline, chebline + + Examples + -------- + >>> from numpy.polynomial.laguerre import lagline, lagval + >>> lagval(0,lagline(3, 2)) + 3.0 + >>> lagval(1,lagline(3, 2)) + 5.0 + + """ + if scl != 0 : + return np.array([off + scl, -scl]) + else : + return np.array([off]) + + +def lagfromroots(roots) : + """ + Generate a Laguerre series with the given roots. + + Return the array of coefficients for the P-series whose roots (a.k.a. + "zeros") are given by *roots*. The returned array of coefficients is + ordered from lowest order "term" to highest, and zeros of multiplicity + greater than one must be included in *roots* a number of times equal + to their multiplicity (e.g., if `2` is a root of multiplicity three, + then [2,2,2] must be in *roots*). + + Parameters + ---------- + roots : array_like + Sequence containing the roots. + + Returns + ------- + out : ndarray + 1-d array of the Laguerre series coefficients, ordered from low to + high. If all roots are real, ``out.dtype`` is a float type; + otherwise, ``out.dtype`` is a complex type, even if all the + coefficients in the result are real (see Examples below). + + See Also + -------- + polyfromroots, chebfromroots + + Notes + ----- + What is returned are the :math:`c_i` such that: + + .. math:: + + \\sum_{i=0}^{n} c_i*P_i(x) = \\prod_{i=0}^{n} (x - roots[i]) + + where ``n == len(roots)`` and :math:`P_i(x)` is the `i`-th Laguerre + (basis) polynomial over the domain `[-1,1]`. Note that, unlike + `polyfromroots`, due to the nature of the Laguerre basis set, the + above identity *does not* imply :math:`c_n = 1` identically (see + Examples). + + Examples + -------- + >>> from numpy.polynomial.laguerre import lagfromroots, lagval + >>> coef = lagfromroots((-1, 0, 1)) + >>> lagval((-1, 0, 1), coef) + array([ 0., 0., 0.]) + >>> coef = lagfromroots((-1j, 1j)) + >>> lagval((-1j, 1j), coef) + array([ 0.+0.j, 0.+0.j]) + + """ + if len(roots) == 0 : + return np.ones(1) + else : + [roots] = pu.as_series([roots], trim=False) + prd = np.array([1], dtype=roots.dtype) + for r in roots: + prd = lagsub(lagmulx(prd), r*prd) + return prd + + +def lagadd(c1, c2): + """ + Add one Laguerre series to another. + + Returns the sum of two Laguerre series `c1` + `c2`. The arguments + are sequences of coefficients ordered from lowest order term to + highest, i.e., [1,2,3] represents the series ``P_0 + 2*P_1 + 3*P_2``. + + Parameters + ---------- + c1, c2 : array_like + 1-d arrays of Laguerre series coefficients ordered from low to + high. + + Returns + ------- + out : ndarray + Array representing the Laguerre series of their sum. + + See Also + -------- + lagsub, lagmul, lagdiv, lagpow + + Notes + ----- + Unlike multiplication, division, etc., the sum of two Laguerre series + is a Laguerre series (without having to "reproject" the result onto + the basis set) so addition, just like that of "standard" polynomials, + is simply "component-wise." + + Examples + -------- + >>> from numpy.polynomial.laguerre import lagadd + >>> lagadd([1, 2, 3], [1, 2, 3, 4]) + array([ 2., 4., 6., 4.]) + + + """ + # c1, c2 are trimmed copies + [c1, c2] = pu.as_series([c1, c2]) + if len(c1) > len(c2) : + c1[:c2.size] += c2 + ret = c1 + else : + c2[:c1.size] += c1 + ret = c2 + return pu.trimseq(ret) + + +def lagsub(c1, c2): + """ + Subtract one Laguerre series from another. + + Returns the difference of two Laguerre series `c1` - `c2`. The + sequences of coefficients are from lowest order term to highest, i.e., + [1,2,3] represents the series ``P_0 + 2*P_1 + 3*P_2``. + + Parameters + ---------- + c1, c2 : array_like + 1-d arrays of Laguerre series coefficients ordered from low to + high. + + Returns + ------- + out : ndarray + Of Laguerre series coefficients representing their difference. + + See Also + -------- + lagadd, lagmul, lagdiv, lagpow + + Notes + ----- + Unlike multiplication, division, etc., the difference of two Laguerre + series is a Laguerre series (without having to "reproject" the result + onto the basis set) so subtraction, just like that of "standard" + polynomials, is simply "component-wise." + + Examples + -------- + >>> from numpy.polynomial.laguerre import lagsub + >>> lagsub([1, 2, 3, 4], [1, 2, 3]) + array([ 0., 0., 0., 4.]) + + """ + # c1, c2 are trimmed copies + [c1, c2] = pu.as_series([c1, c2]) + if len(c1) > len(c2) : + c1[:c2.size] -= c2 + ret = c1 + else : + c2 = -c2 + c2[:c1.size] += c1 + ret = c2 + return pu.trimseq(ret) + + +def lagmulx(cs): + """Multiply a Laguerre series by x. + + Multiply the Laguerre series `cs` by x, where x is the independent + variable. + + + Parameters + ---------- + cs : array_like + 1-d array of Laguerre series coefficients ordered from low to + high. + + Returns + ------- + out : ndarray + Array representing the result of the multiplication. + + Notes + ----- + The multiplication uses the recursion relationship for Laguerre + polynomials in the form + + .. math:: + + xP_i(x) = (-(i + 1)*P_{i + 1}(x) + (2i + 1)P_{i}(x) - iP_{i - 1}(x)) + + Examples + -------- + >>> from numpy.polynomial.laguerre import lagmulx + >>> lagmulx([1, 2, 3]) + array([ -1., -1., 11., -9.]) + + """ + # cs is a trimmed copy + [cs] = pu.as_series([cs]) + # The zero series needs special treatment + if len(cs) == 1 and cs[0] == 0: + return cs + + prd = np.empty(len(cs) + 1, dtype=cs.dtype) + prd[0] = cs[0] + prd[1] = -cs[0] + for i in range(1, len(cs)): + prd[i + 1] = -cs[i]*(i + 1) + prd[i] += cs[i]*(2*i + 1) + prd[i - 1] -= cs[i]*i + return prd + + +def lagmul(c1, c2): + """ + Multiply one Laguerre series by another. + + Returns the product of two Laguerre series `c1` * `c2`. The arguments + are sequences of coefficients, from lowest order "term" to highest, + e.g., [1,2,3] represents the series ``P_0 + 2*P_1 + 3*P_2``. + + Parameters + ---------- + c1, c2 : array_like + 1-d arrays of Laguerre series coefficients ordered from low to + high. + + Returns + ------- + out : ndarray + Of Laguerre series coefficients representing their product. + + See Also + -------- + lagadd, lagsub, lagdiv, lagpow + + Notes + ----- + In general, the (polynomial) product of two C-series results in terms + that are not in the Laguerre polynomial basis set. Thus, to express + the product as a Laguerre series, it is necessary to "re-project" the + product onto said basis set, which may produce "un-intuitive" (but + correct) results; see Examples section below. + + Examples + -------- + >>> from numpy.polynomial.laguerre import lagmul + >>> lagmul([1, 2, 3], [0, 1, 2]) + array([ 8., -13., 38., -51., 36.]) + + """ + # s1, s2 are trimmed copies + [c1, c2] = pu.as_series([c1, c2]) + + if len(c1) > len(c2): + cs = c2 + xs = c1 + else: + cs = c1 + xs = c2 + + if len(cs) == 1: + c0 = cs[0]*xs + c1 = 0 + elif len(cs) == 2: + c0 = cs[0]*xs + c1 = cs[1]*xs + else : + nd = len(cs) + c0 = cs[-2]*xs + c1 = cs[-1]*xs + for i in range(3, len(cs) + 1) : + tmp = c0 + nd = nd - 1 + c0 = lagsub(cs[-i]*xs, (c1*(nd - 1))/nd) + c1 = lagadd(tmp, lagsub((2*nd - 1)*c1, lagmulx(c1))/nd) + return lagadd(c0, lagsub(c1, lagmulx(c1))) + + +def lagdiv(c1, c2): + """ + Divide one Laguerre series by another. + + Returns the quotient-with-remainder of two Laguerre series + `c1` / `c2`. The arguments are sequences of coefficients from lowest + order "term" to highest, e.g., [1,2,3] represents the series + ``P_0 + 2*P_1 + 3*P_2``. + + Parameters + ---------- + c1, c2 : array_like + 1-d arrays of Laguerre series coefficients ordered from low to + high. + + Returns + ------- + [quo, rem] : ndarrays + Of Laguerre series coefficients representing the quotient and + remainder. + + See Also + -------- + lagadd, lagsub, lagmul, lagpow + + Notes + ----- + In general, the (polynomial) division of one Laguerre series by another + results in quotient and remainder terms that are not in the Laguerre + polynomial basis set. Thus, to express these results as a Laguerre + series, it is necessary to "re-project" the results onto the Laguerre + basis set, which may produce "un-intuitive" (but correct) results; see + Examples section below. + + Examples + -------- + >>> from numpy.polynomial.laguerre import lagdiv + >>> lagdiv([ 8., -13., 38., -51., 36.], [0, 1, 2]) + (array([ 1., 2., 3.]), array([ 0.])) + >>> lagdiv([ 9., -12., 38., -51., 36.], [0, 1, 2]) + (array([ 1., 2., 3.]), array([ 1., 1.])) + + """ + # c1, c2 are trimmed copies + [c1, c2] = pu.as_series([c1, c2]) + if c2[-1] == 0 : + raise ZeroDivisionError() + + lc1 = len(c1) + lc2 = len(c2) + if lc1 < lc2 : + return c1[:1]*0, c1 + elif lc2 == 1 : + return c1/c2[-1], c1[:1]*0 + else : + quo = np.empty(lc1 - lc2 + 1, dtype=c1.dtype) + rem = c1 + for i in range(lc1 - lc2, - 1, -1): + p = lagmul([0]*i + [1], c2) + q = rem[-1]/p[-1] + rem = rem[:-1] - q*p[:-1] + quo[i] = q + return quo, pu.trimseq(rem) + + +def lagpow(cs, pow, maxpower=16) : + """Raise a Laguerre series to a power. + + Returns the Laguerre series `cs` raised to the power `pow`. The + arguement `cs` is a sequence of coefficients ordered from low to high. + i.e., [1,2,3] is the series ``P_0 + 2*P_1 + 3*P_2.`` + + Parameters + ---------- + cs : array_like + 1d array of Laguerre series coefficients ordered from low to + high. + pow : integer + Power to which the series will be raised + maxpower : integer, optional + Maximum power allowed. This is mainly to limit growth of the series + to umanageable size. Default is 16 + + Returns + ------- + coef : ndarray + Laguerre series of power. + + See Also + -------- + lagadd, lagsub, lagmul, lagdiv + + Examples + -------- + >>> from numpy.polynomial.laguerre import lagpow + >>> lagpow([1, 2, 3], 2) + array([ 14., -16., 56., -72., 54.]) + + """ + # cs is a trimmed copy + [cs] = pu.as_series([cs]) + power = int(pow) + if power != pow or power < 0 : + raise ValueError("Power must be a non-negative integer.") + elif maxpower is not None and power > maxpower : + raise ValueError("Power is too large") + elif power == 0 : + return np.array([1], dtype=cs.dtype) + elif power == 1 : + return cs + else : + # This can be made more efficient by using powers of two + # in the usual way. + prd = cs + for i in range(2, power + 1) : + prd = lagmul(prd, cs) + return prd + + +def lagder(cs, m=1, scl=1) : + """ + Differentiate a Laguerre series. + + Returns the series `cs` differentiated `m` times. At each iteration the + result is multiplied by `scl` (the scaling factor is for use in a linear + change of variable). The argument `cs` is the sequence of coefficients + from lowest order "term" to highest, e.g., [1,2,3] represents the series + ``P_0 + 2*P_1 + 3*P_2``. + + Parameters + ---------- + cs: array_like + 1-d array of Laguerre series coefficients ordered from low to high. + m : int, optional + Number of derivatives taken, must be non-negative. (Default: 1) + scl : scalar, optional + Each differentiation is multiplied by `scl`. The end result is + multiplication by ``scl**m``. This is for use in a linear change of + variable. (Default: 1) + + Returns + ------- + der : ndarray + Laguerre series of the derivative. + + See Also + -------- + lagint + + Notes + ----- + In general, the result of differentiating a Laguerre series does not + resemble the same operation on a power series. Thus the result of this + function may be "un-intuitive," albeit correct; see Examples section + below. + + Examples + -------- + >>> from numpy.polynomial.laguerre import lagder + >>> lagder([ 1., 1., 1., -3.]) + array([ 1., 2., 3.]) + >>> lagder([ 1., 0., 0., -4., 3.], m=2) + array([ 1., 2., 3.]) + + """ + cnt = int(m) + + if cnt != m: + raise ValueError, "The order of derivation must be integer" + if cnt < 0 : + raise ValueError, "The order of derivation must be non-negative" + + # cs is a trimmed copy + [cs] = pu.as_series([cs]) + if cnt == 0: + return cs + elif cnt >= len(cs): + return cs[:1]*0 + else : + for i in range(cnt): + n = len(cs) - 1 + cs *= scl + der = np.empty(n, dtype=cs.dtype) + for j in range(n, 0, -1): + der[j - 1] = -cs[j] + cs[j - 1] += cs[j] + cs = der + return cs + + +def lagint(cs, m=1, k=[], lbnd=0, scl=1): + """ + Integrate a Laguerre series. + + Returns a Laguerre series that is the Laguerre series `cs`, integrated + `m` times from `lbnd` to `x`. At each iteration the resulting series + is **multiplied** by `scl` and an integration constant, `k`, is added. + The scaling factor is for use in a linear change of variable. ("Buyer + beware": note that, depending on what one is doing, one may want `scl` + to be the reciprocal of what one might expect; for more information, + see the Notes section below.) The argument `cs` is a sequence of + coefficients, from lowest order Laguerre series "term" to highest, + e.g., [1,2,3] represents the series :math:`P_0(x) + 2P_1(x) + 3P_2(x)`. + + Parameters + ---------- + cs : array_like + 1-d array of Laguerre series coefficients, ordered from low to high. + m : int, optional + Order of integration, must be positive. (Default: 1) + k : {[], list, scalar}, optional + Integration constant(s). The value of the first integral at + ``lbnd`` is the first value in the list, the value of the second + integral at ``lbnd`` is the second value, etc. If ``k == []`` (the + default), all constants are set to zero. If ``m == 1``, a single + scalar can be given instead of a list. + lbnd : scalar, optional + The lower bound of the integral. (Default: 0) + scl : scalar, optional + Following each integration the result is *multiplied* by `scl` + before the integration constant is added. (Default: 1) + + Returns + ------- + S : ndarray + Laguerre series coefficients of the integral. + + Raises + ------ + ValueError + If ``m < 0``, ``len(k) > m``, ``np.isscalar(lbnd) == False``, or + ``np.isscalar(scl) == False``. + + See Also + -------- + lagder + + Notes + ----- + Note that the result of each integration is *multiplied* by `scl`. + Why is this important to note? Say one is making a linear change of + variable :math:`u = ax + b` in an integral relative to `x`. Then + :math:`dx = du/a`, so one will need to set `scl` equal to :math:`1/a` + - perhaps not what one would have first thought. + + Also note that, in general, the result of integrating a C-series needs + to be "re-projected" onto the C-series basis set. Thus, typically, + the result of this function is "un-intuitive," albeit correct; see + Examples section below. + + Examples + -------- + >>> from numpy.polynomial.laguerre import lagint + >>> lagint([1,2,3]) + array([ 1., 1., 1., -3.]) + >>> lagint([1,2,3], m=2) + array([ 1., 0., 0., -4., 3.]) + >>> lagint([1,2,3], k=1) + array([ 2., 1., 1., -3.]) + >>> lagint([1,2,3], lbnd=-1) + array([ 11.5, 1. , 1. , -3. ]) + >>> lagint([1,2], m=2, k=[1,2], lbnd=-1) + array([ 11.16666667, -5. , -3. , 2. ]) + + """ + cnt = int(m) + if np.isscalar(k) : + k = [k] + + if cnt != m: + raise ValueError, "The order of integration must be integer" + if cnt < 0 : + raise ValueError, "The order of integration must be non-negative" + if len(k) > cnt : + raise ValueError, "Too many integration constants" + + # cs is a trimmed copy + [cs] = pu.as_series([cs]) + if cnt == 0: + return cs + + k = list(k) + [0]*(cnt - len(k)) + for i in range(cnt) : + n = len(cs) + cs *= scl + if n == 1 and cs[0] == 0: + cs[0] += k[i] + else: + tmp = np.empty(n + 1, dtype=cs.dtype) + tmp[0] = cs[0] + tmp[1] = -cs[0] + for j in range(1, n): + tmp[j] += cs[j] + tmp[j + 1] = -cs[j] + tmp[0] += k[i] - lagval(lbnd, tmp) + cs = tmp + return cs + + +def lagval(x, cs): + """Evaluate a Laguerre series. + + If `cs` is of length `n`, this function returns : + + ``p(x) = cs[0]*P_0(x) + cs[1]*P_1(x) + ... + cs[n-1]*P_{n-1}(x)`` + + If x is a sequence or array then p(x) will have the same shape as x. + If r is a ring_like object that supports multiplication and addition + by the values in `cs`, then an object of the same type is returned. + + Parameters + ---------- + x : array_like, ring_like + Array of numbers or objects that support multiplication and + addition with themselves and with the elements of `cs`. + cs : array_like + 1-d array of Laguerre coefficients ordered from low to high. + + Returns + ------- + values : ndarray, ring_like + If the return is an ndarray then it has the same shape as `x`. + + See Also + -------- + lagfit + + Examples + -------- + + Notes + ----- + The evaluation uses Clenshaw recursion, aka synthetic division. + + Examples + -------- + >>> from numpy.polynomial.laguerre import lagval + >>> coef = [1,2,3] + >>> lagval(1, coef) + -0.5 + >>> lagval([[1,2],[3,4]], coef) + array([[-0.5, -4. ], + [-4.5, -2. ]]) + + """ + # cs is a trimmed copy + [cs] = pu.as_series([cs]) + if isinstance(x, tuple) or isinstance(x, list) : + x = np.asarray(x) + + if len(cs) == 1 : + c0 = cs[0] + c1 = 0 + elif len(cs) == 2 : + c0 = cs[0] + c1 = cs[1] + else : + nd = len(cs) + c0 = cs[-2] + c1 = cs[-1] + for i in range(3, len(cs) + 1) : + tmp = c0 + nd = nd - 1 + c0 = cs[-i] - (c1*(nd - 1))/nd + c1 = tmp + (c1*((2*nd - 1) - x))/nd + return c0 + c1*(1 - x) + + +def lagvander(x, deg) : + """Vandermonde matrix of given degree. + + Returns the Vandermonde matrix of degree `deg` and sample points `x`. + This isn't a true Vandermonde matrix because `x` can be an arbitrary + ndarray and the Laguerre polynomials aren't powers. If ``V`` is the + returned matrix and `x` is a 2d array, then the elements of ``V`` are + ``V[i,j,k] = P_k(x[i,j])``, where ``P_k`` is the Laguerre polynomial + of degree ``k``. + + Parameters + ---------- + x : array_like + Array of points. The values are converted to double or complex + doubles. If x is scalar it is converted to a 1D array. + deg : integer + Degree of the resulting matrix. + + Returns + ------- + vander : Vandermonde matrix. + The shape of the returned matrix is ``x.shape + (deg+1,)``. The last + index is the degree. + + Examples + -------- + >>> from numpy.polynomial.laguerre import lagvander + >>> x = np.array([0, 1, 2]) + >>> lagvander(x, 3) + array([[ 1. , 1. , 1. , 1. ], + [ 1. , 0. , -0.5 , -0.66666667], + [ 1. , -1. , -1. , -0.33333333]]) + + """ + ideg = int(deg) + if ideg != deg: + raise ValueError("deg must be integer") + if ideg < 0: + raise ValueError("deg must be non-negative") + + x = np.array(x, copy=0, ndmin=1) + 0.0 + v = np.empty((ideg + 1,) + x.shape, dtype=x.dtype) + v[0] = x*0 + 1 + if ideg > 0 : + v[1] = 1 - x + for i in range(2, ideg + 1) : + v[i] = (v[i-1]*(2*i - 1 - x) - v[i-2]*(i - 1))/i + return np.rollaxis(v, 0, v.ndim) + + +def lagfit(x, y, deg, rcond=None, full=False, w=None): + """ + Least squares fit of Laguerre series to data. + + Fit a Laguerre series ``p(x) = p[0] * P_{0}(x) + ... + p[deg] * + P_{deg}(x)`` of degree `deg` to points `(x, y)`. Returns a vector of + coefficients `p` that minimises the squared error. + + Parameters + ---------- + x : array_like, shape (M,) + x-coordinates of the M sample points ``(x[i], y[i])``. + y : array_like, shape (M,) or (M, K) + y-coordinates of the sample points. Several data sets of sample + points sharing the same x-coordinates can be fitted at once by + passing in a 2D-array that contains one dataset per column. + deg : int + Degree of the fitting polynomial + rcond : float, optional + Relative condition number of the fit. Singular values smaller than + this relative to the largest singular value will be ignored. The + default value is len(x)*eps, where eps is the relative precision of + the float type, about 2e-16 in most cases. + full : bool, optional + Switch determining nature of return value. When it is False (the + default) just the coefficients are returned, when True diagnostic + information from the singular value decomposition is also returned. + w : array_like, shape (`M`,), optional + Weights. If not None, the contribution of each point + ``(x[i],y[i])`` to the fit is weighted by `w[i]`. Ideally the + weights are chosen so that the errors of the products ``w[i]*y[i]`` + all have the same variance. The default value is None. + + Returns + ------- + coef : ndarray, shape (M,) or (M, K) + Laguerre coefficients ordered from low to high. If `y` was 2-D, + the coefficients for the data in column k of `y` are in column + `k`. + + [residuals, rank, singular_values, rcond] : present when `full` = True + Residuals of the least-squares fit, the effective rank of the + scaled Vandermonde matrix and its singular values, and the + specified value of `rcond`. For more details, see `linalg.lstsq`. + + Warns + ----- + RankWarning + The rank of the coefficient matrix in the least-squares fit is + deficient. The warning is only raised if `full` = False. The + warnings can be turned off by + + >>> import warnings + >>> warnings.simplefilter('ignore', RankWarning) + + See Also + -------- + lagval : Evaluates a Laguerre series. + lagvander : Vandermonde matrix of Laguerre series. + polyfit : least squares fit using polynomials. + chebfit : least squares fit using Chebyshev series. + linalg.lstsq : Computes a least-squares fit from the matrix. + scipy.interpolate.UnivariateSpline : Computes spline fits. + + Notes + ----- + The solution are the coefficients ``c[i]`` of the Laguerre series + ``P(x)`` that minimizes the squared error + + ``E = \\sum_j |y_j - P(x_j)|^2``. + + This problem is solved by setting up as the overdetermined matrix + equation + + ``V(x)*c = y``, + + where ``V`` is the Vandermonde matrix of `x`, the elements of ``c`` are + the coefficients to be solved for, and the elements of `y` are the + observed values. This equation is then solved using the singular value + decomposition of ``V``. + + If some of the singular values of ``V`` are so small that they are + neglected, then a `RankWarning` will be issued. This means that the + coeficient values may be poorly determined. Using a lower order fit + will usually get rid of the warning. The `rcond` parameter can also be + set to a value smaller than its default, but the resulting fit may be + spurious and have large contributions from roundoff error. + + Fits using Laguerre series are usually better conditioned than fits + using power series, but much can depend on the distribution of the + sample points and the smoothness of the data. If the quality of the fit + is inadequate splines may be a good alternative. + + References + ---------- + .. [1] Wikipedia, "Curve fitting", + http://en.wikipedia.org/wiki/Curve_fitting + + Examples + -------- + >>> from numpy.polynomial.laguerre import lagfit, lagval + >>> x = np.linspace(0, 10) + >>> err = np.random.randn(len(x))/10 + >>> y = lagval(x, [1, 2, 3]) + err + >>> lagfit(x, y, 2) + array([ 0.96971004, 2.00193749, 3.00288744]) + + """ + order = int(deg) + 1 + x = np.asarray(x) + 0.0 + y = np.asarray(y) + 0.0 + + # check arguments. + if deg < 0 : + raise ValueError, "expected deg >= 0" + if x.ndim != 1: + raise TypeError, "expected 1D vector for x" + if x.size == 0: + raise TypeError, "expected non-empty vector for x" + if y.ndim < 1 or y.ndim > 2 : + raise TypeError, "expected 1D or 2D array for y" + if len(x) != len(y): + raise TypeError, "expected x and y to have same length" + + # set up the least squares matrices + lhs = lagvander(x, deg) + rhs = y + if w is not None: + w = np.asarray(w) + 0.0 + if w.ndim != 1: + raise TypeError, "expected 1D vector for w" + if len(x) != len(w): + raise TypeError, "expected x and w to have same length" + # apply weights + if rhs.ndim == 2: + lhs *= w[:, np.newaxis] + rhs *= w[:, np.newaxis] + else: + lhs *= w[:, np.newaxis] + rhs *= w + + # set rcond + if rcond is None : + rcond = len(x)*np.finfo(x.dtype).eps + + # scale the design matrix and solve the least squares equation + scl = np.sqrt((lhs*lhs).sum(0)) + c, resids, rank, s = la.lstsq(lhs/scl, rhs, rcond) + c = (c.T/scl).T + + # warn on rank reduction + if rank != order and not full: + msg = "The fit may be poorly conditioned" + warnings.warn(msg, pu.RankWarning) + + if full : + return c, [resids, rank, s, rcond] + else : + return c + + +def lagroots(cs): + """ + Compute the roots of a Laguerre series. + + Return the roots (a.k.a "zeros") of the Laguerre series represented by + `cs`, which is the sequence of coefficients from lowest order "term" + to highest, e.g., [1,2,3] is the series ``L_0 + 2*L_1 + 3*L_2``. + + Parameters + ---------- + cs : array_like + 1-d array of Laguerre series coefficients ordered from low to high. + + Returns + ------- + out : ndarray + Array of the roots. If all the roots are real, then so is the + dtype of ``out``; otherwise, ``out``'s dtype is complex. + + See Also + -------- + polyroots + chebroots + + Notes + ----- + Algorithm(s) used: + + Remember: because the Laguerre series basis set is different from the + "standard" basis set, the results of this function *may* not be what + one is expecting. + + Examples + -------- + >>> from numpy.polynomial.laguerre import lagroots, lagfromroots + >>> coef = lagfromroots([0, 1, 2]) + >>> coef + array([ 2., -8., 12., -6.]) + >>> lagroots(coef) + array([ -4.44089210e-16, 1.00000000e+00, 2.00000000e+00]) + + """ + # cs is a trimmed copy + [cs] = pu.as_series([cs]) + if len(cs) <= 1 : + return np.array([], dtype=cs.dtype) + if len(cs) == 2 : + return np.array([1 + cs[0]/cs[1]]) + + n = len(cs) - 1 + cs /= cs[-1] + cmat = np.zeros((n,n), dtype=cs.dtype) + cmat[0, 0] = 1 + cmat[1, 0] = -1 + for i in range(1, n): + cmat[i - 1, i] = -i + cmat[i, i] = 2*i + 1 + if i != n - 1: + cmat[i + 1, i] = -(i + 1) + else: + cmat[:, i] += cs[:-1]*(i + 1) + roots = la.eigvals(cmat) + roots.sort() + return roots + + +# +# Laguerre series class +# + +exec polytemplate.substitute(name='Laguerre', nick='lag', domain='[-1,1]') diff --git a/numpy/polynomial/legendre.py b/numpy/polynomial/legendre.py index 9aec256cd..3ea68a5e6 100644 --- a/numpy/polynomial/legendre.py +++ b/numpy/polynomial/legendre.py @@ -227,52 +227,6 @@ def legline(off, scl) : return np.array([off]) -def legtimesx(cs): - """Multiply a Legendre series by x. - - Multiply the Legendre series `cs` by x, where x is the independent - variable. - - - Parameters - ---------- - cs : array_like - 1-d array of Legendre series coefficients ordered from low to - high. - - Returns - ------- - out : ndarray - Array representing the result of the multiplication. - - Notes - ----- - The multiplication uses the recursion relationship for Legendre - polynomials in the form - - .. math:: - - xP_i(x) = ((i + 1)*P_{i + 1}(x) + i*P_{i - 1}(x))/(2i + 1) - - """ - # cs is a trimmed copy - [cs] = pu.as_series([cs]) - # The zero series needs special treatment - if len(cs) == 1 and cs[0] == 0: - return cs - - prd = np.empty(len(cs) + 1, dtype=cs.dtype) - prd[0] = cs[0]*0 - prd[1] = cs[0] - for i in range(1, len(cs)): - j = i + 1 - k = i - 1 - s = i + j - prd[j] = (cs[i]*j)/s - prd[k] += (cs[i]*i)/s - return prd - - def legfromroots(roots) : """ Generate a Legendre series with the given roots. diff --git a/numpy/polynomial/polytemplate.py b/numpy/polynomial/polytemplate.py index 2106ad84e..657b48508 100644 --- a/numpy/polynomial/polytemplate.py +++ b/numpy/polynomial/polytemplate.py @@ -31,16 +31,22 @@ class $name(pu.PolyBase) : $name coefficients, in increasing order. For example, ``(1, 2, 3)`` implies ``P_0 + 2P_1 + 3P_2`` where the ``P_i`` are a graded polynomial basis. - domain : (2,) array_like + domain : (2,) array_like, optional Domain to use. The interval ``[domain[0], domain[1]]`` is mapped to - the interval ``$domain`` by shifting and scaling. + the interval ``[window[0], window[1]]`` by shifting and scaling. + The default value is $domain. + window : (2,) array_like, optional + Window, see ``domain`` for its use. The default value is $domain. + .. versionadded:: 1.6.0 Attributes ---------- coef : (N,) array $name coefficients, from low to high. - domain : (2,) array_like - Domain that is mapped to ``$domain``. + domain : (2,) array + Domain that is mapped to ``window``. + window : (2,) array + Window that ``domain`` is mapped to. Class Attributes ---------------- @@ -49,6 +55,8 @@ class $name(pu.PolyBase) : ``p(x)**n`` is allowed. This is to limit runaway polynomial size. domain : (2,) ndarray Default domain of the class. + window : (2,) ndarray + Default window of the class. Notes ----- @@ -65,25 +73,115 @@ class $name(pu.PolyBase) : maxpower = 16 # Default domain domain = np.array($domain) + # Default window + window = np.array($domain) # Don't let participate in array operations. Value doesn't matter. __array_priority__ = 0 - def __init__(self, coef, domain=$domain) : - [coef, domain] = pu.as_series([coef, domain], trim=False) - if len(domain) != 2 : + def has_samecoef(self, other): + """Check if coefficients match. + + Parameters + ---------- + other : class instance + The other class must have the ``coef`` attribute. + + Returns + ------- + bool : boolean + True if the coefficients are the same, False otherwise. + + Notes + ----- + .. versionadded:: 1.6.0 + + """ + if len(self.coef) != len(other.coef): + return False + elif not np.all(self.coef == other.coef): + return False + else: + return True + + def has_samedomain(self, other): + """Check if domains match. + + Parameters + ---------- + other : class instance + The other class must have the ``domain`` attribute. + + Returns + ------- + bool : boolean + True if the domains are the same, False otherwise. + + Notes + ----- + .. versionadded:: 1.6.0 + + """ + return np.all(self.domain == other.domain) + + def has_samewindow(self, other): + """Check if windows match. + + Parameters + ---------- + other : class instance + The other class must have the ``window`` attribute. + + Returns + ------- + bool : boolean + True if the windows are the same, False otherwise. + + Notes + ----- + .. versionadded:: 1.6.0 + + """ + return np.all(self.window == other.window) + + def has_samewindow(self, other): + """Check if windows match. + + Parameters + ---------- + other : class instance + The other class must have the ``window`` attribute. + + Returns + ------- + bool : boolean + True if the windows are the same, False otherwise. + + """ + return np.all(self.window == other.window) + + def __init__(self, coef, domain=$domain, window=$domain) : + [coef, dom, win] = pu.as_series([coef, domain, window], trim=False) + if len(dom) != 2 : raise ValueError("Domain has wrong number of elements.") + if len(win) != 2 : + raise ValueError("Window has wrong number of elements.") self.coef = coef - self.domain = domain + self.domain = dom + self.window = win def __repr__(self): - format = "%s(%s, %s)" + format = "%s(%s, %s, %s)" coef = repr(self.coef)[6:-1] domain = repr(self.domain)[6:-1] - return format % ('$name', coef, domain) + window = repr(self.domain)[6:-1] + return format % ('$name', coef, domain, window) def __str__(self) : - format = "%s(%s, %s)" - return format % ('$nick', str(self.coef), str(self.domain)) + format = "%s(%s, %s, %s)" + coef = str(self.coef)[6:-1] + domain = str(self.domain)[6:-1] + window = str(self.domain)[6:-1] + return format % ('$nick', coef, domain, window) # Pickle and copy @@ -91,6 +189,7 @@ class $name(pu.PolyBase) : ret = self.__dict__.copy() ret['coef'] = self.coef.copy() ret['domain'] = self.domain.copy() + ret['window'] = self.window.copy() return ret def __setstate__(self, dict) : @@ -99,11 +198,10 @@ class $name(pu.PolyBase) : # Call def __call__(self, arg) : - off, scl = pu.mapparms(self.domain, $domain) + off, scl = pu.mapparms(self.domain, self.window) arg = off + scl*arg return ${nick}val(arg, self.coef) - def __iter__(self) : return iter(self.coef) @@ -112,9 +210,8 @@ class $name(pu.PolyBase) : # Numeric properties. - def __neg__(self) : - return self.__class__(-self.coef, self.domain) + return self.__class__(-self.coef, self.domain, self.window) def __pos__(self) : return self @@ -122,7 +219,7 @@ class $name(pu.PolyBase) : def __add__(self, other) : """Returns sum""" if isinstance(other, self.__class__) : - if np.all(self.domain == other.domain) : + if self.has_samedomain(other) and self.has_samewindow(other): coef = ${nick}add(self.coef, other.coef) else : raise PolyDomainError() @@ -131,12 +228,12 @@ class $name(pu.PolyBase) : coef = ${nick}add(self.coef, other) except : return NotImplemented - return self.__class__(coef, self.domain) + return self.__class__(coef, self.domain, self.window) def __sub__(self, other) : """Returns difference""" if isinstance(other, self.__class__) : - if np.all(self.domain == other.domain) : + if self.has_samedomain(other) and self.has_samewindow(other): coef = ${nick}sub(self.coef, other.coef) else : raise PolyDomainError() @@ -145,12 +242,12 @@ class $name(pu.PolyBase) : coef = ${nick}sub(self.coef, other) except : return NotImplemented - return self.__class__(coef, self.domain) + return self.__class__(coef, self.domain, self.window) def __mul__(self, other) : """Returns product""" if isinstance(other, self.__class__) : - if np.all(self.domain == other.domain) : + if self.has_samedomain(other) and self.has_samewindow(other): coef = ${nick}mul(self.coef, other.coef) else : raise PolyDomainError() @@ -159,7 +256,7 @@ class $name(pu.PolyBase) : coef = ${nick}mul(self.coef, other) except : return NotImplemented - return self.__class__(coef, self.domain) + return self.__class__(coef, self.domain, self.window) def __div__(self, other): # set to __floordiv__ /. @@ -175,10 +272,11 @@ class $name(pu.PolyBase) : else : return NotImplemented elif np.isscalar(other) : + # this might be overly restrictive coef = self.coef/other else : return NotImplemented - return self.__class__(coef, self.domain) + return self.__class__(coef, self.domain, self.window) def __floordiv__(self, other) : """Returns the quotient.""" @@ -192,12 +290,12 @@ class $name(pu.PolyBase) : quo, rem = ${nick}div(self.coef, other) except : return NotImplemented - return self.__class__(quo, self.domain) + return self.__class__(quo, self.domain, self.window) def __mod__(self, other) : """Returns the remainder.""" if isinstance(other, self.__class__) : - if np.all(self.domain == other.domain) : + if self.has_samedomain(other) and self.has_samewindow(other): quo, rem = ${nick}div(self.coef, other.coef) else : raise PolyDomainError() @@ -206,12 +304,12 @@ class $name(pu.PolyBase) : quo, rem = ${nick}div(self.coef, other) except : return NotImplemented - return self.__class__(rem, self.domain) + return self.__class__(rem, self.domain, self.window) def __divmod__(self, other) : """Returns quo, remainder""" if isinstance(other, self.__class__) : - if np.all(self.domain == other.domain) : + if self.has_samedomain(other) and self.has_samewindow(other): quo, rem = ${nick}div(self.coef, other.coef) else : raise PolyDomainError() @@ -220,35 +318,37 @@ class $name(pu.PolyBase) : quo, rem = ${nick}div(self.coef, other) except : return NotImplemented - return self.__class__(quo, self.domain), self.__class__(rem, self.domain) + quo = self.__class__(quo, self.domain, self.window) + rem = self.__class__(rem, self.domain, self.window) + return quo, rem def __pow__(self, other) : try : coef = ${nick}pow(self.coef, other, maxpower = self.maxpower) except : raise - return self.__class__(coef, self.domain) + return self.__class__(coef, self.domain, self.window) def __radd__(self, other) : try : coef = ${nick}add(other, self.coef) except : return NotImplemented - return self.__class__(coef, self.domain) + return self.__class__(coef, self.domain, self.window) def __rsub__(self, other): try : coef = ${nick}sub(other, self.coef) except : return NotImplemented - return self.__class__(coef, self.domain) + return self.__class__(coef, self.domain, self.window) def __rmul__(self, other) : try : coef = ${nick}mul(other, self.coef) except : return NotImplemented - return self.__class__(coef, self.domain) + return self.__class__(coef, self.domain, self.window) def __rdiv__(self, other): # set to __floordiv__ /. @@ -263,46 +363,62 @@ class $name(pu.PolyBase) : quo, rem = ${nick}div(other, self.coef[0]) except : return NotImplemented - return self.__class__(quo, self.domain) + return self.__class__(quo, self.domain, self.window) def __rfloordiv__(self, other) : try : quo, rem = ${nick}div(other, self.coef) except : return NotImplemented - return self.__class__(quo, self.domain) + return self.__class__(quo, self.domain, self.window) def __rmod__(self, other) : try : quo, rem = ${nick}div(other, self.coef) except : return NotImplemented - return self.__class__(rem, self.domain) + return self.__class__(rem, self.domain, self.window) def __rdivmod__(self, other) : try : quo, rem = ${nick}div(other, self.coef) except : return NotImplemented - return self.__class__(quo, self.domain), self.__class__(rem, self.domain) + quo = self.__class__(quo, self.domain, self.window) + rem = self.__class__(rem, self.domain, self.window) + return quo, rem # Enhance me # some augmented arithmetic operations could be added here def __eq__(self, other) : res = isinstance(other, self.__class__) \ - and len(self.coef) == len(other.coef) \ - and np.all(self.domain == other.domain) \ - and np.all(self.coef == other.coef) + and self.has_samecoef(other) \ + and self.has_samedomain(other) \ + and self.has_samewindow(other) return res def __ne__(self, other) : return not self.__eq__(other) # - # Extra numeric functions. + # Extra methods. # + def copy(self) : + """Return a copy. + + A new instance of $name is returned that has the same + coefficients and domain as the current instance. + + Returns + ------- + new_instance : $name + New instance of $name with the same coefficients and domain. + + """ + return self.__class__(self.coef, self.domain, self.window) + def degree(self) : """The degree of the series. @@ -340,68 +456,6 @@ class $name(pu.PolyBase) : """ return self.truncate(deg + 1) - def convert(self, domain=None, kind=None) : - """Convert to different class and/or domain. - - Parameters - ---------- - domain : array_like, optional - The domain of the new series type instance. If the value is None, - then the default domain of `kind` is used. - kind : class, optional - The polynomial series type class to which the current instance - should be converted. If kind is None, then the class of the - current instance is used. - - Returns - ------- - new_series_instance : `kind` - The returned class can be of different type than the current - instance and/or have a different domain. - - Notes - ----- - Conversion between domains and class types can result in - numerically ill defined series. - - Examples - -------- - - """ - if kind is None : - kind = $name - if domain is None : - domain = kind.domain - return self(kind.identity(domain)) - - def mapparms(self) : - """Return the mapping parameters. - - The returned values define a linear map ``off + scl*x`` that is - applied to the input arguments before the series is evaluated. The - of the map depend on the domain; if the current domain is equal to - the default domain ``$domain`` the resulting map is the identity. - If the coeffients of the ``$name`` instance are to be used - separately, then the linear function must be substituted for the - ``x`` in the standard representation of the base polynomials. - - Returns - ------- - off, scl : floats or complex - The mapping function is defined by ``off + scl*x``. - - Notes - ----- - If the current domain is the interval ``[l_1, r_1]`` and the default - interval is ``[l_2, r_2]``, then the linear mapping function ``L`` is - defined by the equations:: - - L(l_1) = l_2 - L(r_1) = r_2 - - """ - return pu.mapparms(self.domain, $domain) - def trim(self, tol=0) : """Remove small leading coefficients @@ -422,7 +476,8 @@ class $name(pu.PolyBase) : Contains the new set of coefficients. """ - return self.__class__(pu.trimcoef(self.coef, tol), self.domain) + coef = pu.trimcoef(self.coef, tol) + return self.__class__(coef, self.domain, self.window) def truncate(self, size) : """Truncate series to length `size`. @@ -448,23 +503,75 @@ class $name(pu.PolyBase) : if isize != size or isize < 1 : raise ValueError("size must be a positive integer") if isize >= len(self.coef) : - return self.__class__(self.coef, self.domain) + coef = self.coef else : - return self.__class__(self.coef[:isize], self.domain) + coef = self.coef[:isize] + return self.__class__(coef, self.domain, self.window) - def copy(self) : - """Return a copy. + def convert(self, domain=None, kind=None, window=None) : + """Convert to different class and/or domain. - A new instance of $name is returned that has the same - coefficients and domain as the current instance. + Parameters + ---------- + domain : array_like, optional + The domain of the new series type instance. If the value is None, + then the default domain of `kind` is used. + kind : class, optional + The polynomial series type class to which the current instance + should be converted. If kind is None, then the class of the + current instance is used. Returns ------- - new_instance : $name - New instance of $name with the same coefficients and domain. + new_series_instance : `kind` + The returned class can be of different type than the current + instance and/or have a different domain. + + Notes + ----- + Conversion between domains and class types can result in + numerically ill defined series. + + Examples + -------- + + """ + if kind is None: + kind = $name + if domain is None: + domain = kind.domain + if window is None: + window = kind.window + return self(kind.identity(domain, window=window)) + + def mapparms(self) : + """Return the mapping parameters. + + The returned values define a linear map ``off + scl*x`` that is + applied to the input arguments before the series is evaluated. The + map depends on the ``domain`` and ``window``; if the current + ``domain`` is equal to the ``window`` the resulting map is the + identity. If the coeffients of the ``$name`` instance are to be + used by themselves outside this class, then the linear function + must be substituted for the ``x`` in the standard representation of + the base polynomials. + + Returns + ------- + off, scl : floats or complex + The mapping function is defined by ``off + scl*x``. + + Notes + ----- + If the current domain is the interval ``[l_1, r_1]`` and the window + is ``[l_2, r_2]``, then the linear mapping function ``L`` is + defined by the equations:: + + L(l_1) = l_2 + L(r_1) = r_2 """ - return self.__class__(self.coef, self.domain) + return pu.mapparms(self.domain, self.window) def integ(self, m=1, k=[], lbnd=None) : """Integrate. @@ -501,7 +608,7 @@ class $name(pu.PolyBase) : else : lbnd = off + scl*lbnd coef = ${nick}int(self.coef, m, k, lbnd, 1./scl) - return self.__class__(coef, self.domain) + return self.__class__(coef, self.domain, self.window) def deriv(self, m=1): """Differentiate. @@ -527,7 +634,7 @@ class $name(pu.PolyBase) : """ off, scl = self.mapparms() coef = ${nick}der(self.coef, m, scl) - return self.__class__(coef, self.domain) + return self.__class__(coef, self.domain, self.window) def roots(self) : """Return list of roots. @@ -543,9 +650,9 @@ class $name(pu.PolyBase) : """ roots = ${nick}roots(self.coef) - return pu.mapdomain(roots, $domain, self.domain) + return pu.mapdomain(roots, self.window, self.domain) - def linspace(self, n=100): + def linspace(self, n=100, domain=None): """Return x,y values at equally spaced points in domain. Returns x, y values at `n` equally spaced points across domain. @@ -566,14 +673,17 @@ class $name(pu.PolyBase) : .. versionadded:: 1.5.0 """ - x = np.linspace(self.domain[0], self.domain[1], n) + if domain is None: + domain = self.domain + x = np.linspace(domain[0], domain[1], n) y = self(x) return x, y @staticmethod - def fit(x, y, deg, domain=None, rcond=None, full=False, w=None) : + def fit(x, y, deg, domain=None, rcond=None, full=False, w=None, + window=$domain): """Least squares fit to data. Return a `$name` instance that is the least squares fit to the data @@ -616,6 +726,10 @@ class $name(pu.PolyBase) : ``w[i]*y[i]`` all have the same variance. The default value is None. .. versionadded:: 1.5.0 + window : {[beg, end]}, optional + Window to use for the returned $name instance. The default + value is ``$domain`` + .. versionadded:: 1.6.0 Returns ------- @@ -634,21 +748,25 @@ class $name(pu.PolyBase) : ${nick}fit : similar function """ - if domain is None : + if domain is None: domain = pu.getdomain(x) - elif domain == [] : + elif domain == []: domain = $domain - xnew = pu.mapdomain(x, domain, $domain) + + if window == []: + window = $domain + + xnew = pu.mapdomain(x, domain, window) res = ${nick}fit(xnew, y, deg, w=w, rcond=rcond, full=full) if full : [coef, status] = res - return $name(coef, domain=domain), status + return $name(coef, domain=domain, window=window), status else : coef = res - return $name(coef, domain=domain) + return $name(coef, domain=domain, window=window) @staticmethod - def fromroots(roots, domain=$domain) : + def fromroots(roots, domain=$domain, window=$domain) : """Return $name object with specified roots. See ${nick}fromroots for full documentation. @@ -660,12 +778,12 @@ class $name(pu.PolyBase) : """ if domain is None : domain = pu.getdomain(roots) - rnew = pu.mapdomain(roots, domain, $domain) + rnew = pu.mapdomain(roots, domain, window) coef = ${nick}fromroots(rnew) - return $name(coef, domain=domain) + return $name(coef, domain=domain, window=window) @staticmethod - def identity(domain=$domain) : + def identity(domain=$domain, window=$domain) : """Identity function. If ``p`` is the returned $name object, then ``p(x) == x`` for all @@ -676,13 +794,16 @@ class $name(pu.PolyBase) : domain : array_like The resulting array must be if the form ``[beg, end]``, where ``beg`` and ``end`` are the endpoints of the domain. + window : array_like + The resulting array must be if the form ``[beg, end]``, where + ``beg`` and ``end`` are the endpoints of the window. Returns ------- identity : $name object """ - off, scl = pu.mapparms($domain, domain) + off, scl = pu.mapparms(window, domain) coef = ${nick}line(off, scl) - return $name(coef, domain) + return $name(coef, domain, window) '''.replace('REL_IMPORT', rel_import)) diff --git a/numpy/polynomial/tests/test_chebyshev.py b/numpy/polynomial/tests/test_chebyshev.py index 65bb877f4..21e4728bf 100644 --- a/numpy/polynomial/tests/test_chebyshev.py +++ b/numpy/polynomial/tests/test_chebyshev.py @@ -462,7 +462,7 @@ class TestChebyshevClass(TestCase) : def test_degree(self) : assert_equal(self.p1.degree(), 2) - def test_trimdeg(self) : + def test_cutdeg(self) : assert_raises(ValueError, self.p1.cutdeg, .5) assert_raises(ValueError, self.p1.cutdeg, -1) assert_equal(len(self.p1.cutdeg(3)), 3) @@ -564,3 +564,7 @@ class TestChebyshevClass(TestCase) : assert_almost_equal(p(x), x) p = ch.Chebyshev.identity([1,3]) assert_almost_equal(p(x), x) +# + +if __name__ == "__main__": + run_module_suite() diff --git a/numpy/polynomial/tests/test_hermite.py b/numpy/polynomial/tests/test_hermite.py new file mode 100644 index 000000000..dea32f24a --- /dev/null +++ b/numpy/polynomial/tests/test_hermite.py @@ -0,0 +1,537 @@ +"""Tests for hermendre module. + +""" +from __future__ import division + +import numpy as np +import numpy.polynomial.hermite as herm +import numpy.polynomial.polynomial as poly +from numpy.testing import * + +H0 = np.array([ 1]) +H1 = np.array([0, 2]) +H2 = np.array([ -2, 0, 4]) +H3 = np.array([0, -12, 0, 8]) +H4 = np.array([ 12, 0, -48, 0, 16]) +H5 = np.array([0, 120, 0, -160, 0, 32]) +H6 = np.array([-120, 0, 720, 0, -480, 0, 64]) +H7 = np.array([0, -1680, 0, 3360, 0, -1344, 0, 128]) +H8 = np.array([1680, 0, -13440, 0, 13440, 0, -3584, 0, 256]) +H9 = np.array([0, 30240, 0, -80640, 0, 48384, 0, -9216, 0, 512]) + +Hlist = [H0, H1, H2, H3, H4, H5, H6, H7, H8, H9] + + +def trim(x) : + return herm.hermtrim(x, tol=1e-6) + + +class TestConstants(TestCase) : + + def test_hermdomain(self) : + assert_equal(herm.hermdomain, [-1, 1]) + + def test_hermzero(self) : + assert_equal(herm.hermzero, [0]) + + def test_hermone(self) : + assert_equal(herm.hermone, [1]) + + def test_hermx(self) : + assert_equal(herm.hermx, [0, .5]) + + +class TestArithmetic(TestCase) : + x = np.linspace(-3, 3, 100) + y0 = poly.polyval(x, H0) + y1 = poly.polyval(x, H1) + y2 = poly.polyval(x, H2) + y3 = poly.polyval(x, H3) + y4 = poly.polyval(x, H4) + y5 = poly.polyval(x, H5) + y6 = poly.polyval(x, H6) + y7 = poly.polyval(x, H7) + y8 = poly.polyval(x, H8) + y9 = poly.polyval(x, H9) + y = [y0, y1, y2, y3, y4, y5, y6, y7, y8, y9] + + def test_hermval(self) : + def f(x) : + return x*(x**2 - 1) + + #check empty input + assert_equal(herm.hermval([], [1]).size, 0) + + #check normal input) + for i in range(10) : + msg = "At i=%d" % i + ser = np.zeros + tgt = self.y[i] + res = herm.hermval(self.x, [0]*i + [1]) + assert_almost_equal(res, tgt, err_msg=msg) + + #check that shape is preserved + for i in range(3) : + dims = [2]*i + x = np.zeros(dims) + assert_equal(herm.hermval(x, [1]).shape, dims) + assert_equal(herm.hermval(x, [1,0]).shape, dims) + assert_equal(herm.hermval(x, [1,0,0]).shape, dims) + + def test_hermadd(self) : + for i in range(5) : + for j in range(5) : + msg = "At i=%d, j=%d" % (i,j) + tgt = np.zeros(max(i,j) + 1) + tgt[i] += 1 + tgt[j] += 1 + res = herm.hermadd([0]*i + [1], [0]*j + [1]) + assert_equal(trim(res), trim(tgt), err_msg=msg) + + def test_hermsub(self) : + for i in range(5) : + for j in range(5) : + msg = "At i=%d, j=%d" % (i,j) + tgt = np.zeros(max(i,j) + 1) + tgt[i] += 1 + tgt[j] -= 1 + res = herm.hermsub([0]*i + [1], [0]*j + [1]) + assert_equal(trim(res), trim(tgt), err_msg=msg) + + def test_hermmulx(self): + assert_equal(herm.hermmulx([0]), [0]) + assert_equal(herm.hermmulx([1]), [0,.5]) + for i in range(1, 5): + ser = [0]*i + [1] + tgt = [0]*(i - 1) + [i, 0, .5] + assert_equal(herm.hermmulx(ser), tgt) + + def test_hermmul(self) : + # check values of result + for i in range(5) : + pol1 = [0]*i + [1] + val1 = herm.hermval(self.x, pol1) + for j in range(5) : + msg = "At i=%d, j=%d" % (i,j) + pol2 = [0]*j + [1] + val2 = herm.hermval(self.x, pol2) + pol3 = herm.hermmul(pol1, pol2) + val3 = herm.hermval(self.x, pol3) + assert_(len(pol3) == i + j + 1, msg) + assert_almost_equal(val3, val1*val2, err_msg=msg) + + def test_hermdiv(self) : + for i in range(5) : + for j in range(5) : + msg = "At i=%d, j=%d" % (i,j) + ci = [0]*i + [1] + cj = [0]*j + [1] + tgt = herm.hermadd(ci, cj) + quo, rem = herm.hermdiv(tgt, ci) + res = herm.hermadd(herm.hermmul(quo, ci), rem) + assert_equal(trim(res), trim(tgt), err_msg=msg) + + +class TestCalculus(TestCase) : + + def test_hermint(self) : + # check exceptions + assert_raises(ValueError, herm.hermint, [0], .5) + assert_raises(ValueError, herm.hermint, [0], -1) + assert_raises(ValueError, herm.hermint, [0], 1, [0,0]) + + # test integration of zero polynomial + for i in range(2, 5): + k = [0]*(i - 2) + [1] + res = herm.hermint([0], m=i, k=k) + assert_almost_equal(res, [0, .5]) + + # check single integration with integration constant + for i in range(5) : + scl = i + 1 + pol = [0]*i + [1] + tgt = [i] + [0]*i + [1/scl] + hermpol = herm.poly2herm(pol) + hermint = herm.hermint(hermpol, m=1, k=[i]) + res = herm.herm2poly(hermint) + assert_almost_equal(trim(res), trim(tgt)) + + # check single integration with integration constant and lbnd + for i in range(5) : + scl = i + 1 + pol = [0]*i + [1] + hermpol = herm.poly2herm(pol) + hermint = herm.hermint(hermpol, m=1, k=[i], lbnd=-1) + assert_almost_equal(herm.hermval(-1, hermint), i) + + # check single integration with integration constant and scaling + for i in range(5) : + scl = i + 1 + pol = [0]*i + [1] + tgt = [i] + [0]*i + [2/scl] + hermpol = herm.poly2herm(pol) + hermint = herm.hermint(hermpol, m=1, k=[i], scl=2) + res = herm.herm2poly(hermint) + assert_almost_equal(trim(res), trim(tgt)) + + # check multiple integrations with default k + for i in range(5) : + for j in range(2,5) : + pol = [0]*i + [1] + tgt = pol[:] + for k in range(j) : + tgt = herm.hermint(tgt, m=1) + res = herm.hermint(pol, m=j) + assert_almost_equal(trim(res), trim(tgt)) + + # check multiple integrations with defined k + for i in range(5) : + for j in range(2,5) : + pol = [0]*i + [1] + tgt = pol[:] + for k in range(j) : + tgt = herm.hermint(tgt, m=1, k=[k]) + res = herm.hermint(pol, m=j, k=range(j)) + assert_almost_equal(trim(res), trim(tgt)) + + # check multiple integrations with lbnd + for i in range(5) : + for j in range(2,5) : + pol = [0]*i + [1] + tgt = pol[:] + for k in range(j) : + tgt = herm.hermint(tgt, m=1, k=[k], lbnd=-1) + res = herm.hermint(pol, m=j, k=range(j), lbnd=-1) + assert_almost_equal(trim(res), trim(tgt)) + + # check multiple integrations with scaling + for i in range(5) : + for j in range(2,5) : + pol = [0]*i + [1] + tgt = pol[:] + for k in range(j) : + tgt = herm.hermint(tgt, m=1, k=[k], scl=2) + res = herm.hermint(pol, m=j, k=range(j), scl=2) + assert_almost_equal(trim(res), trim(tgt)) + + def test_hermder(self) : + # check exceptions + assert_raises(ValueError, herm.hermder, [0], .5) + assert_raises(ValueError, herm.hermder, [0], -1) + + # check that zeroth deriviative does nothing + for i in range(5) : + tgt = [1] + [0]*i + res = herm.hermder(tgt, m=0) + assert_equal(trim(res), trim(tgt)) + + # check that derivation is the inverse of integration + for i in range(5) : + for j in range(2,5) : + tgt = [1] + [0]*i + res = herm.hermder(herm.hermint(tgt, m=j), m=j) + assert_almost_equal(trim(res), trim(tgt)) + + # check derivation with scaling + for i in range(5) : + for j in range(2,5) : + tgt = [1] + [0]*i + res = herm.hermder(herm.hermint(tgt, m=j, scl=2), m=j, scl=.5) + assert_almost_equal(trim(res), trim(tgt)) + + +class TestMisc(TestCase) : + + def test_hermfromroots(self) : + res = herm.hermfromroots([]) + assert_almost_equal(trim(res), [1]) + for i in range(1,5) : + roots = np.cos(np.linspace(-np.pi, 0, 2*i + 1)[1::2]) + pol = herm.hermfromroots(roots) + res = herm.hermval(roots, pol) + tgt = 0 + assert_(len(pol) == i + 1) + assert_almost_equal(herm.herm2poly(pol)[-1], 1) + assert_almost_equal(res, tgt) + + def test_hermroots(self) : + assert_almost_equal(herm.hermroots([1]), []) + assert_almost_equal(herm.hermroots([1, 1]), [-.5]) + for i in range(2,5) : + tgt = np.linspace(-1, 1, i) + res = herm.hermroots(herm.hermfromroots(tgt)) + assert_almost_equal(trim(res), trim(tgt)) + + def test_hermvander(self) : + # check for 1d x + x = np.arange(3) + v = herm.hermvander(x, 3) + assert_(v.shape == (3,4)) + for i in range(4) : + coef = [0]*i + [1] + assert_almost_equal(v[...,i], herm.hermval(x, coef)) + + # check for 2d x + x = np.array([[1,2],[3,4],[5,6]]) + v = herm.hermvander(x, 3) + assert_(v.shape == (3,2,4)) + for i in range(4) : + coef = [0]*i + [1] + assert_almost_equal(v[...,i], herm.hermval(x, coef)) + + def test_hermfit(self) : + def f(x) : + return x*(x - 1)*(x - 2) + + # Test exceptions + assert_raises(ValueError, herm.hermfit, [1], [1], -1) + assert_raises(TypeError, herm.hermfit, [[1]], [1], 0) + assert_raises(TypeError, herm.hermfit, [], [1], 0) + assert_raises(TypeError, herm.hermfit, [1], [[[1]]], 0) + assert_raises(TypeError, herm.hermfit, [1, 2], [1], 0) + assert_raises(TypeError, herm.hermfit, [1], [1, 2], 0) + assert_raises(TypeError, herm.hermfit, [1], [1], 0, w=[[1]]) + assert_raises(TypeError, herm.hermfit, [1], [1], 0, w=[1,1]) + + # Test fit + x = np.linspace(0,2) + y = f(x) + # + coef3 = herm.hermfit(x, y, 3) + assert_equal(len(coef3), 4) + assert_almost_equal(herm.hermval(x, coef3), y) + # + coef4 = herm.hermfit(x, y, 4) + assert_equal(len(coef4), 5) + assert_almost_equal(herm.hermval(x, coef4), y) + # + coef2d = herm.hermfit(x, np.array([y,y]).T, 3) + assert_almost_equal(coef2d, np.array([coef3,coef3]).T) + # test weighting + w = np.zeros_like(x) + yw = y.copy() + w[1::2] = 1 + y[0::2] = 0 + wcoef3 = herm.hermfit(x, yw, 3, w=w) + assert_almost_equal(wcoef3, coef3) + # + wcoef2d = herm.hermfit(x, np.array([yw,yw]).T, 3, w=w) + assert_almost_equal(wcoef2d, np.array([coef3,coef3]).T) + + def test_hermtrim(self) : + coef = [2, -1, 1, 0] + + # Test exceptions + assert_raises(ValueError, herm.hermtrim, coef, -1) + + # Test results + assert_equal(herm.hermtrim(coef), coef[:-1]) + assert_equal(herm.hermtrim(coef, 1), coef[:-3]) + assert_equal(herm.hermtrim(coef, 2), [0]) + + def test_hermline(self) : + assert_equal(herm.hermline(3,4), [3, 2]) + + def test_herm2poly(self) : + for i in range(10) : + assert_almost_equal(herm.herm2poly([0]*i + [1]), Hlist[i]) + + def test_poly2herm(self) : + for i in range(10) : + assert_almost_equal(herm.poly2herm(Hlist[i]), [0]*i + [1]) + + +def assert_poly_almost_equal(p1, p2): + assert_almost_equal(p1.coef, p2.coef) + assert_equal(p1.domain, p2.domain) + + +class TestHermiteClass(TestCase) : + + p1 = herm.Hermite([1,2,3]) + p2 = herm.Hermite([1,2,3], [0,1]) + p3 = herm.Hermite([1,2]) + p4 = herm.Hermite([2,2,3]) + p5 = herm.Hermite([3,2,3]) + + def test_equal(self) : + assert_(self.p1 == self.p1) + assert_(self.p2 == self.p2) + assert_(not self.p1 == self.p2) + assert_(not self.p1 == self.p3) + assert_(not self.p1 == [1,2,3]) + + def test_not_equal(self) : + assert_(not self.p1 != self.p1) + assert_(not self.p2 != self.p2) + assert_(self.p1 != self.p2) + assert_(self.p1 != self.p3) + assert_(self.p1 != [1,2,3]) + + def test_add(self) : + tgt = herm.Hermite([2,4,6]) + assert_(self.p1 + self.p1 == tgt) + assert_(self.p1 + [1,2,3] == tgt) + assert_([1,2,3] + self.p1 == tgt) + + def test_sub(self) : + tgt = herm.Hermite([1]) + assert_(self.p4 - self.p1 == tgt) + assert_(self.p4 - [1,2,3] == tgt) + assert_([2,2,3] - self.p1 == tgt) + + def test_mul(self) : + tgt = herm.Hermite([ 81., 52., 82., 12., 9.]) + assert_poly_almost_equal(self.p1 * self.p1, tgt) + assert_poly_almost_equal(self.p1 * [1,2,3], tgt) + assert_poly_almost_equal([1,2,3] * self.p1, tgt) + + def test_floordiv(self) : + tgt = herm.Hermite([1]) + assert_(self.p4 // self.p1 == tgt) + assert_(self.p4 // [1,2,3] == tgt) + assert_([2,2,3] // self.p1 == tgt) + + def test_mod(self) : + tgt = herm.Hermite([1]) + assert_((self.p4 % self.p1) == tgt) + assert_((self.p4 % [1,2,3]) == tgt) + assert_(([2,2,3] % self.p1) == tgt) + + def test_divmod(self) : + tquo = herm.Hermite([1]) + trem = herm.Hermite([2]) + quo, rem = divmod(self.p5, self.p1) + assert_(quo == tquo and rem == trem) + quo, rem = divmod(self.p5, [1,2,3]) + assert_(quo == tquo and rem == trem) + quo, rem = divmod([3,2,3], self.p1) + assert_(quo == tquo and rem == trem) + + def test_pow(self) : + tgt = herm.Hermite([1]) + for i in range(5) : + res = self.p1**i + assert_(res == tgt) + tgt = tgt*self.p1 + + def test_call(self) : + # domain = [-1, 1] + x = np.linspace(-1, 1) + tgt = 3*(4*x**2 - 2) + 2*(2*x) + 1 + assert_almost_equal(self.p1(x), tgt) + + # domain = [0, 1] + x = np.linspace(0, 1) + xx = 2*x - 1 + assert_almost_equal(self.p2(x), self.p1(xx)) + + def test_degree(self) : + assert_equal(self.p1.degree(), 2) + + def test_cutdeg(self) : + assert_raises(ValueError, self.p1.cutdeg, .5) + assert_raises(ValueError, self.p1.cutdeg, -1) + assert_equal(len(self.p1.cutdeg(3)), 3) + assert_equal(len(self.p1.cutdeg(2)), 3) + assert_equal(len(self.p1.cutdeg(1)), 2) + assert_equal(len(self.p1.cutdeg(0)), 1) + + def test_convert(self) : + x = np.linspace(-1,1) + p = self.p1.convert(domain=[0,1]) + assert_almost_equal(p(x), self.p1(x)) + + def test_mapparms(self) : + parms = self.p2.mapparms() + assert_almost_equal(parms, [-1, 2]) + + def test_trim(self) : + coef = [1, 1e-6, 1e-12, 0] + p = herm.Hermite(coef) + assert_equal(p.trim().coef, coef[:3]) + assert_equal(p.trim(1e-10).coef, coef[:2]) + assert_equal(p.trim(1e-5).coef, coef[:1]) + + def test_truncate(self) : + assert_raises(ValueError, self.p1.truncate, .5) + assert_raises(ValueError, self.p1.truncate, 0) + assert_equal(len(self.p1.truncate(4)), 3) + assert_equal(len(self.p1.truncate(3)), 3) + assert_equal(len(self.p1.truncate(2)), 2) + assert_equal(len(self.p1.truncate(1)), 1) + + def test_copy(self) : + p = self.p1.copy() + assert_(self.p1 == p) + + def test_integ(self) : + p = self.p2.integ() + assert_almost_equal(p.coef, herm.hermint([1,2,3], 1, 0, scl=.5)) + p = self.p2.integ(lbnd=0) + assert_almost_equal(p(0), 0) + p = self.p2.integ(1, 1) + assert_almost_equal(p.coef, herm.hermint([1,2,3], 1, 1, scl=.5)) + p = self.p2.integ(2, [1, 2]) + assert_almost_equal(p.coef, herm.hermint([1,2,3], 2, [1,2], scl=.5)) + + def test_deriv(self) : + p = self.p2.integ(2, [1, 2]) + assert_almost_equal(p.deriv(1).coef, self.p2.integ(1, [1]).coef) + assert_almost_equal(p.deriv(2).coef, self.p2.coef) + + def test_roots(self) : + p = herm.Hermite(herm.poly2herm([0, -1, 0, 1]), [0, 1]) + res = p.roots() + tgt = [0, .5, 1] + assert_almost_equal(res, tgt) + + def test_linspace(self): + xdes = np.linspace(0, 1, 20) + ydes = self.p2(xdes) + xres, yres = self.p2.linspace(20) + assert_almost_equal(xres, xdes) + assert_almost_equal(yres, ydes) + + def test_fromroots(self) : + roots = [0, .5, 1] + p = herm.Hermite.fromroots(roots, domain=[0, 1]) + res = p.coef + tgt = herm.poly2herm([0, -1, 0, 1]) + assert_almost_equal(res, tgt) + + def test_fit(self) : + def f(x) : + return x*(x - 1)*(x - 2) + x = np.linspace(0,3) + y = f(x) + + # test default value of domain + p = herm.Hermite.fit(x, y, 3) + assert_almost_equal(p.domain, [0,3]) + + # test that fit works in given domains + p = herm.Hermite.fit(x, y, 3, None) + assert_almost_equal(p(x), y) + assert_almost_equal(p.domain, [0,3]) + p = herm.Hermite.fit(x, y, 3, []) + assert_almost_equal(p(x), y) + assert_almost_equal(p.domain, [-1, 1]) + # test that fit accepts weights. + w = np.zeros_like(x) + yw = y.copy() + w[1::2] = 1 + yw[0::2] = 0 + p = herm.Hermite.fit(x, yw, 3, w=w) + assert_almost_equal(p(x), y) + + def test_identity(self) : + x = np.linspace(0,3) + p = herm.Hermite.identity() + assert_almost_equal(p(x), x) + p = herm.Hermite.identity([1,3]) + assert_almost_equal(p(x), x) +# + +if __name__ == "__main__": + run_module_suite() diff --git a/numpy/polynomial/tests/test_hermite_e.py b/numpy/polynomial/tests/test_hermite_e.py new file mode 100644 index 000000000..6026e0e64 --- /dev/null +++ b/numpy/polynomial/tests/test_hermite_e.py @@ -0,0 +1,536 @@ +"""Tests for hermeendre module. + +""" +from __future__ import division + +import numpy as np +import numpy.polynomial.hermite_e as herme +import numpy.polynomial.polynomial as poly +from numpy.testing import * + +He0 = np.array([ 1 ]) +He1 = np.array([ 0 , 1 ]) +He2 = np.array([ -1 ,0 , 1 ]) +He3 = np.array([ 0 , -3 ,0 , 1 ]) +He4 = np.array([ 3 ,0 , -6 ,0 , 1 ]) +He5 = np.array([ 0 , 15 ,0 , -10 ,0 , 1 ]) +He6 = np.array([ -15 ,0 , 45 ,0 , -15 ,0 , 1 ]) +He7 = np.array([ 0 , -105 ,0 , 105 ,0 , -21 ,0 , 1 ]) +He8 = np.array([ 105 ,0 , -420 ,0 , 210 ,0 , -28 ,0 , 1 ]) +He9 = np.array([ 0 , 945 ,0 , -1260 ,0 , 378 ,0 , -36 ,0 , 1 ]) + +Helist = [He0, He1, He2, He3, He4, He5, He6, He7, He8, He9] + +def trim(x) : + return herme.hermetrim(x, tol=1e-6) + + +class TestConstants(TestCase) : + + def test_hermedomain(self) : + assert_equal(herme.hermedomain, [-1, 1]) + + def test_hermezero(self) : + assert_equal(herme.hermezero, [0]) + + def test_hermeone(self) : + assert_equal(herme.hermeone, [1]) + + def test_hermex(self) : + assert_equal(herme.hermex, [0, 1]) + + +class TestArithmetic(TestCase) : + x = np.linspace(-3, 3, 100) + y0 = poly.polyval(x, He0) + y1 = poly.polyval(x, He1) + y2 = poly.polyval(x, He2) + y3 = poly.polyval(x, He3) + y4 = poly.polyval(x, He4) + y5 = poly.polyval(x, He5) + y6 = poly.polyval(x, He6) + y7 = poly.polyval(x, He7) + y8 = poly.polyval(x, He8) + y9 = poly.polyval(x, He9) + y = [y0, y1, y2, y3, y4, y5, y6, y7, y8, y9] + + def test_hermeval(self) : + def f(x) : + return x*(x**2 - 1) + + #check empty input + assert_equal(herme.hermeval([], [1]).size, 0) + + #check normal input) + for i in range(10) : + msg = "At i=%d" % i + ser = np.zeros + tgt = self.y[i] + res = herme.hermeval(self.x, [0]*i + [1]) + assert_almost_equal(res, tgt, err_msg=msg) + + #check that shape is preserved + for i in range(3) : + dims = [2]*i + x = np.zeros(dims) + assert_equal(herme.hermeval(x, [1]).shape, dims) + assert_equal(herme.hermeval(x, [1,0]).shape, dims) + assert_equal(herme.hermeval(x, [1,0,0]).shape, dims) + + def test_hermeadd(self) : + for i in range(5) : + for j in range(5) : + msg = "At i=%d, j=%d" % (i,j) + tgt = np.zeros(max(i,j) + 1) + tgt[i] += 1 + tgt[j] += 1 + res = herme.hermeadd([0]*i + [1], [0]*j + [1]) + assert_equal(trim(res), trim(tgt), err_msg=msg) + + def test_hermesub(self) : + for i in range(5) : + for j in range(5) : + msg = "At i=%d, j=%d" % (i,j) + tgt = np.zeros(max(i,j) + 1) + tgt[i] += 1 + tgt[j] -= 1 + res = herme.hermesub([0]*i + [1], [0]*j + [1]) + assert_equal(trim(res), trim(tgt), err_msg=msg) + + def test_hermemulx(self): + assert_equal(herme.hermemulx([0]), [0]) + assert_equal(herme.hermemulx([1]), [0,1]) + for i in range(1, 5): + ser = [0]*i + [1] + tgt = [0]*(i - 1) + [i, 0, 1] + assert_equal(herme.hermemulx(ser), tgt) + + def test_hermemul(self) : + # check values of result + for i in range(5) : + pol1 = [0]*i + [1] + val1 = herme.hermeval(self.x, pol1) + for j in range(5) : + msg = "At i=%d, j=%d" % (i,j) + pol2 = [0]*j + [1] + val2 = herme.hermeval(self.x, pol2) + pol3 = herme.hermemul(pol1, pol2) + val3 = herme.hermeval(self.x, pol3) + assert_(len(pol3) == i + j + 1, msg) + assert_almost_equal(val3, val1*val2, err_msg=msg) + + def test_hermediv(self) : + for i in range(5) : + for j in range(5) : + msg = "At i=%d, j=%d" % (i,j) + ci = [0]*i + [1] + cj = [0]*j + [1] + tgt = herme.hermeadd(ci, cj) + quo, rem = herme.hermediv(tgt, ci) + res = herme.hermeadd(herme.hermemul(quo, ci), rem) + assert_equal(trim(res), trim(tgt), err_msg=msg) + + +class TestCalculus(TestCase) : + + def test_hermeint(self) : + # check exceptions + assert_raises(ValueError, herme.hermeint, [0], .5) + assert_raises(ValueError, herme.hermeint, [0], -1) + assert_raises(ValueError, herme.hermeint, [0], 1, [0,0]) + + # test integration of zero polynomial + for i in range(2, 5): + k = [0]*(i - 2) + [1] + res = herme.hermeint([0], m=i, k=k) + assert_almost_equal(res, [0, 1]) + + # check single integration with integration constant + for i in range(5) : + scl = i + 1 + pol = [0]*i + [1] + tgt = [i] + [0]*i + [1/scl] + hermepol = herme.poly2herme(pol) + hermeint = herme.hermeint(hermepol, m=1, k=[i]) + res = herme.herme2poly(hermeint) + assert_almost_equal(trim(res), trim(tgt)) + + # check single integration with integration constant and lbnd + for i in range(5) : + scl = i + 1 + pol = [0]*i + [1] + hermepol = herme.poly2herme(pol) + hermeint = herme.hermeint(hermepol, m=1, k=[i], lbnd=-1) + assert_almost_equal(herme.hermeval(-1, hermeint), i) + + # check single integration with integration constant and scaling + for i in range(5) : + scl = i + 1 + pol = [0]*i + [1] + tgt = [i] + [0]*i + [2/scl] + hermepol = herme.poly2herme(pol) + hermeint = herme.hermeint(hermepol, m=1, k=[i], scl=2) + res = herme.herme2poly(hermeint) + assert_almost_equal(trim(res), trim(tgt)) + + # check multiple integrations with default k + for i in range(5) : + for j in range(2,5) : + pol = [0]*i + [1] + tgt = pol[:] + for k in range(j) : + tgt = herme.hermeint(tgt, m=1) + res = herme.hermeint(pol, m=j) + assert_almost_equal(trim(res), trim(tgt)) + + # check multiple integrations with defined k + for i in range(5) : + for j in range(2,5) : + pol = [0]*i + [1] + tgt = pol[:] + for k in range(j) : + tgt = herme.hermeint(tgt, m=1, k=[k]) + res = herme.hermeint(pol, m=j, k=range(j)) + assert_almost_equal(trim(res), trim(tgt)) + + # check multiple integrations with lbnd + for i in range(5) : + for j in range(2,5) : + pol = [0]*i + [1] + tgt = pol[:] + for k in range(j) : + tgt = herme.hermeint(tgt, m=1, k=[k], lbnd=-1) + res = herme.hermeint(pol, m=j, k=range(j), lbnd=-1) + assert_almost_equal(trim(res), trim(tgt)) + + # check multiple integrations with scaling + for i in range(5) : + for j in range(2,5) : + pol = [0]*i + [1] + tgt = pol[:] + for k in range(j) : + tgt = herme.hermeint(tgt, m=1, k=[k], scl=2) + res = herme.hermeint(pol, m=j, k=range(j), scl=2) + assert_almost_equal(trim(res), trim(tgt)) + + def test_hermeder(self) : + # check exceptions + assert_raises(ValueError, herme.hermeder, [0], .5) + assert_raises(ValueError, herme.hermeder, [0], -1) + + # check that zeroth deriviative does nothing + for i in range(5) : + tgt = [1] + [0]*i + res = herme.hermeder(tgt, m=0) + assert_equal(trim(res), trim(tgt)) + + # check that derivation is the inverse of integration + for i in range(5) : + for j in range(2,5) : + tgt = [1] + [0]*i + res = herme.hermeder(herme.hermeint(tgt, m=j), m=j) + assert_almost_equal(trim(res), trim(tgt)) + + # check derivation with scaling + for i in range(5) : + for j in range(2,5) : + tgt = [1] + [0]*i + res = herme.hermeder(herme.hermeint(tgt, m=j, scl=2), m=j, scl=.5) + assert_almost_equal(trim(res), trim(tgt)) + + +class TestMisc(TestCase) : + + def test_hermefromroots(self) : + res = herme.hermefromroots([]) + assert_almost_equal(trim(res), [1]) + for i in range(1,5) : + roots = np.cos(np.linspace(-np.pi, 0, 2*i + 1)[1::2]) + pol = herme.hermefromroots(roots) + res = herme.hermeval(roots, pol) + tgt = 0 + assert_(len(pol) == i + 1) + assert_almost_equal(herme.herme2poly(pol)[-1], 1) + assert_almost_equal(res, tgt) + + def test_hermeroots(self) : + assert_almost_equal(herme.hermeroots([1]), []) + assert_almost_equal(herme.hermeroots([1, 1]), [-.5]) + for i in range(2,5) : + tgt = np.linspace(-1, 1, i) + res = herme.hermeroots(herme.hermefromroots(tgt)) + assert_almost_equal(trim(res), trim(tgt)) + + def test_hermevander(self) : + # check for 1d x + x = np.arange(3) + v = herme.hermevander(x, 3) + assert_(v.shape == (3,4)) + for i in range(4) : + coef = [0]*i + [1] + assert_almost_equal(v[...,i], herme.hermeval(x, coef)) + + # check for 2d x + x = np.array([[1,2],[3,4],[5,6]]) + v = herme.hermevander(x, 3) + assert_(v.shape == (3,2,4)) + for i in range(4) : + coef = [0]*i + [1] + assert_almost_equal(v[...,i], herme.hermeval(x, coef)) + + def test_hermefit(self) : + def f(x) : + return x*(x - 1)*(x - 2) + + # Test exceptions + assert_raises(ValueError, herme.hermefit, [1], [1], -1) + assert_raises(TypeError, herme.hermefit, [[1]], [1], 0) + assert_raises(TypeError, herme.hermefit, [], [1], 0) + assert_raises(TypeError, herme.hermefit, [1], [[[1]]], 0) + assert_raises(TypeError, herme.hermefit, [1, 2], [1], 0) + assert_raises(TypeError, herme.hermefit, [1], [1, 2], 0) + assert_raises(TypeError, herme.hermefit, [1], [1], 0, w=[[1]]) + assert_raises(TypeError, herme.hermefit, [1], [1], 0, w=[1,1]) + + # Test fit + x = np.linspace(0,2) + y = f(x) + # + coef3 = herme.hermefit(x, y, 3) + assert_equal(len(coef3), 4) + assert_almost_equal(herme.hermeval(x, coef3), y) + # + coef4 = herme.hermefit(x, y, 4) + assert_equal(len(coef4), 5) + assert_almost_equal(herme.hermeval(x, coef4), y) + # + coef2d = herme.hermefit(x, np.array([y,y]).T, 3) + assert_almost_equal(coef2d, np.array([coef3,coef3]).T) + # test weighting + w = np.zeros_like(x) + yw = y.copy() + w[1::2] = 1 + y[0::2] = 0 + wcoef3 = herme.hermefit(x, yw, 3, w=w) + assert_almost_equal(wcoef3, coef3) + # + wcoef2d = herme.hermefit(x, np.array([yw,yw]).T, 3, w=w) + assert_almost_equal(wcoef2d, np.array([coef3,coef3]).T) + + def test_hermetrim(self) : + coef = [2, -1, 1, 0] + + # Test exceptions + assert_raises(ValueError, herme.hermetrim, coef, -1) + + # Test results + assert_equal(herme.hermetrim(coef), coef[:-1]) + assert_equal(herme.hermetrim(coef, 1), coef[:-3]) + assert_equal(herme.hermetrim(coef, 2), [0]) + + def test_hermeline(self) : + assert_equal(herme.hermeline(3,4), [3, 4]) + + def test_herme2poly(self) : + for i in range(10) : + assert_almost_equal(herme.herme2poly([0]*i + [1]), Helist[i]) + + def test_poly2herme(self) : + for i in range(10) : + assert_almost_equal(herme.poly2herme(Helist[i]), [0]*i + [1]) + + +def assert_poly_almost_equal(p1, p2): + assert_almost_equal(p1.coef, p2.coef) + assert_equal(p1.domain, p2.domain) + + +class TestHermiteEClass(TestCase) : + + p1 = herme.HermiteE([1,2,3]) + p2 = herme.HermiteE([1,2,3], [0,1]) + p3 = herme.HermiteE([1,2]) + p4 = herme.HermiteE([2,2,3]) + p5 = herme.HermiteE([3,2,3]) + + def test_equal(self) : + assert_(self.p1 == self.p1) + assert_(self.p2 == self.p2) + assert_(not self.p1 == self.p2) + assert_(not self.p1 == self.p3) + assert_(not self.p1 == [1,2,3]) + + def test_not_equal(self) : + assert_(not self.p1 != self.p1) + assert_(not self.p2 != self.p2) + assert_(self.p1 != self.p2) + assert_(self.p1 != self.p3) + assert_(self.p1 != [1,2,3]) + + def test_add(self) : + tgt = herme.HermiteE([2,4,6]) + assert_(self.p1 + self.p1 == tgt) + assert_(self.p1 + [1,2,3] == tgt) + assert_([1,2,3] + self.p1 == tgt) + + def test_sub(self) : + tgt = herme.HermiteE([1]) + assert_(self.p4 - self.p1 == tgt) + assert_(self.p4 - [1,2,3] == tgt) + assert_([2,2,3] - self.p1 == tgt) + + def test_mul(self) : + tgt = herme.HermiteE([ 23., 28., 46., 12., 9.]) + assert_poly_almost_equal(self.p1 * self.p1, tgt) + assert_poly_almost_equal(self.p1 * [1,2,3], tgt) + assert_poly_almost_equal([1,2,3] * self.p1, tgt) + + def test_floordiv(self) : + tgt = herme.HermiteE([1]) + assert_(self.p4 // self.p1 == tgt) + assert_(self.p4 // [1,2,3] == tgt) + assert_([2,2,3] // self.p1 == tgt) + + def test_mod(self) : + tgt = herme.HermiteE([1]) + assert_((self.p4 % self.p1) == tgt) + assert_((self.p4 % [1,2,3]) == tgt) + assert_(([2,2,3] % self.p1) == tgt) + + def test_divmod(self) : + tquo = herme.HermiteE([1]) + trem = herme.HermiteE([2]) + quo, rem = divmod(self.p5, self.p1) + assert_(quo == tquo and rem == trem) + quo, rem = divmod(self.p5, [1,2,3]) + assert_(quo == tquo and rem == trem) + quo, rem = divmod([3,2,3], self.p1) + assert_(quo == tquo and rem == trem) + + def test_pow(self) : + tgt = herme.HermiteE([1]) + for i in range(5) : + res = self.p1**i + assert_(res == tgt) + tgt = tgt*self.p1 + + def test_call(self) : + # domain = [-1, 1] + x = np.linspace(-1, 1) + tgt = 3*(x**2 - 1) + 2*(x) + 1 + assert_almost_equal(self.p1(x), tgt) + + # domain = [0, 1] + x = np.linspace(0, 1) + xx = 2*x - 1 + assert_almost_equal(self.p2(x), self.p1(xx)) + + def test_degree(self) : + assert_equal(self.p1.degree(), 2) + + def test_cutdeg(self) : + assert_raises(ValueError, self.p1.cutdeg, .5) + assert_raises(ValueError, self.p1.cutdeg, -1) + assert_equal(len(self.p1.cutdeg(3)), 3) + assert_equal(len(self.p1.cutdeg(2)), 3) + assert_equal(len(self.p1.cutdeg(1)), 2) + assert_equal(len(self.p1.cutdeg(0)), 1) + + def test_convert(self) : + x = np.linspace(-1,1) + p = self.p1.convert(domain=[0,1]) + assert_almost_equal(p(x), self.p1(x)) + + def test_mapparms(self) : + parms = self.p2.mapparms() + assert_almost_equal(parms, [-1, 2]) + + def test_trim(self) : + coef = [1, 1e-6, 1e-12, 0] + p = herme.HermiteE(coef) + assert_equal(p.trim().coef, coef[:3]) + assert_equal(p.trim(1e-10).coef, coef[:2]) + assert_equal(p.trim(1e-5).coef, coef[:1]) + + def test_truncate(self) : + assert_raises(ValueError, self.p1.truncate, .5) + assert_raises(ValueError, self.p1.truncate, 0) + assert_equal(len(self.p1.truncate(4)), 3) + assert_equal(len(self.p1.truncate(3)), 3) + assert_equal(len(self.p1.truncate(2)), 2) + assert_equal(len(self.p1.truncate(1)), 1) + + def test_copy(self) : + p = self.p1.copy() + assert_(self.p1 == p) + + def test_integ(self) : + p = self.p2.integ() + assert_almost_equal(p.coef, herme.hermeint([1,2,3], 1, 0, scl=.5)) + p = self.p2.integ(lbnd=0) + assert_almost_equal(p(0), 0) + p = self.p2.integ(1, 1) + assert_almost_equal(p.coef, herme.hermeint([1,2,3], 1, 1, scl=.5)) + p = self.p2.integ(2, [1, 2]) + assert_almost_equal(p.coef, herme.hermeint([1,2,3], 2, [1,2], scl=.5)) + + def test_deriv(self) : + p = self.p2.integ(2, [1, 2]) + assert_almost_equal(p.deriv(1).coef, self.p2.integ(1, [1]).coef) + assert_almost_equal(p.deriv(2).coef, self.p2.coef) + + def test_roots(self) : + p = herme.HermiteE(herme.poly2herme([0, -1, 0, 1]), [0, 1]) + res = p.roots() + tgt = [0, .5, 1] + assert_almost_equal(res, tgt) + + def test_linspace(self): + xdes = np.linspace(0, 1, 20) + ydes = self.p2(xdes) + xres, yres = self.p2.linspace(20) + assert_almost_equal(xres, xdes) + assert_almost_equal(yres, ydes) + + def test_fromroots(self) : + roots = [0, .5, 1] + p = herme.HermiteE.fromroots(roots, domain=[0, 1]) + res = p.coef + tgt = herme.poly2herme([0, -1, 0, 1]) + assert_almost_equal(res, tgt) + + def test_fit(self) : + def f(x) : + return x*(x - 1)*(x - 2) + x = np.linspace(0,3) + y = f(x) + + # test default value of domain + p = herme.HermiteE.fit(x, y, 3) + assert_almost_equal(p.domain, [0,3]) + + # test that fit works in given domains + p = herme.HermiteE.fit(x, y, 3, None) + assert_almost_equal(p(x), y) + assert_almost_equal(p.domain, [0,3]) + p = herme.HermiteE.fit(x, y, 3, []) + assert_almost_equal(p(x), y) + assert_almost_equal(p.domain, [-1, 1]) + # test that fit accepts weights. + w = np.zeros_like(x) + yw = y.copy() + w[1::2] = 1 + yw[0::2] = 0 + p = herme.HermiteE.fit(x, yw, 3, w=w) + assert_almost_equal(p(x), y) + + def test_identity(self) : + x = np.linspace(0,3) + p = herme.HermiteE.identity() + assert_almost_equal(p(x), x) + p = herme.HermiteE.identity([1,3]) + assert_almost_equal(p(x), x) + + +if __name__ == "__main__": + run_module_suite() diff --git a/numpy/polynomial/tests/test_laguerre.py b/numpy/polynomial/tests/test_laguerre.py new file mode 100644 index 000000000..f3a4a930b --- /dev/null +++ b/numpy/polynomial/tests/test_laguerre.py @@ -0,0 +1,530 @@ +"""Tests for hermendre module. + +""" +from __future__ import division + +import numpy as np +import numpy.polynomial.laguerre as lag +import numpy.polynomial.polynomial as poly +from numpy.testing import * + +L0 = np.array([1 ])/1 +L1 = np.array([1 , -1 ])/1 +L2 = np.array([2 , -4 , 1 ])/2 +L3 = np.array([6 , -18 , 9 , -1 ])/6 +L4 = np.array([24 , -96 , 72 , -16 , 1 ])/24 +L5 = np.array([120 , -600 , 600 , -200 , 25 , -1 ])/120 +L6 = np.array([720 , -4320 , 5400 , -2400 , 450 , -36 , 1 ])/720 + +Llist = [L0, L1, L2, L3, L4, L5, L6] + +def trim(x) : + return lag.lagtrim(x, tol=1e-6) + + +class TestConstants(TestCase) : + + def test_lagdomain(self) : + assert_equal(lag.lagdomain, [0, 1]) + + def test_lagzero(self) : + assert_equal(lag.lagzero, [0]) + + def test_lagone(self) : + assert_equal(lag.lagone, [1]) + + def test_lagx(self) : + assert_equal(lag.lagx, [1, -1]) + + +class TestArithmetic(TestCase) : + x = np.linspace(-3, 3, 100) + y0 = poly.polyval(x, L0) + y1 = poly.polyval(x, L1) + y2 = poly.polyval(x, L2) + y3 = poly.polyval(x, L3) + y4 = poly.polyval(x, L4) + y5 = poly.polyval(x, L5) + y6 = poly.polyval(x, L6) + y = [y0, y1, y2, y3, y4, y5, y6] + + def test_lagval(self) : + def f(x) : + return x*(x**2 - 1) + + #check empty input + assert_equal(lag.lagval([], [1]).size, 0) + + #check normal input) + for i in range(7) : + msg = "At i=%d" % i + ser = np.zeros + tgt = self.y[i] + res = lag.lagval(self.x, [0]*i + [1]) + assert_almost_equal(res, tgt, err_msg=msg) + + #check that shape is preserved + for i in range(3) : + dims = [2]*i + x = np.zeros(dims) + assert_equal(lag.lagval(x, [1]).shape, dims) + assert_equal(lag.lagval(x, [1,0]).shape, dims) + assert_equal(lag.lagval(x, [1,0,0]).shape, dims) + + def test_lagadd(self) : + for i in range(5) : + for j in range(5) : + msg = "At i=%d, j=%d" % (i,j) + tgt = np.zeros(max(i,j) + 1) + tgt[i] += 1 + tgt[j] += 1 + res = lag.lagadd([0]*i + [1], [0]*j + [1]) + assert_equal(trim(res), trim(tgt), err_msg=msg) + + def test_lagsub(self) : + for i in range(5) : + for j in range(5) : + msg = "At i=%d, j=%d" % (i,j) + tgt = np.zeros(max(i,j) + 1) + tgt[i] += 1 + tgt[j] -= 1 + res = lag.lagsub([0]*i + [1], [0]*j + [1]) + assert_equal(trim(res), trim(tgt), err_msg=msg) + + def test_lagmulx(self): + assert_equal(lag.lagmulx([0]), [0]) + assert_equal(lag.lagmulx([1]), [1,-1]) + for i in range(1, 5): + ser = [0]*i + [1] + tgt = [0]*(i - 1) + [-i, 2*i + 1, -(i + 1)] + assert_almost_equal(lag.lagmulx(ser), tgt) + + def test_lagmul(self) : + # check values of result + for i in range(5) : + pol1 = [0]*i + [1] + val1 = lag.lagval(self.x, pol1) + for j in range(5) : + msg = "At i=%d, j=%d" % (i,j) + pol2 = [0]*j + [1] + val2 = lag.lagval(self.x, pol2) + pol3 = lag.lagmul(pol1, pol2) + val3 = lag.lagval(self.x, pol3) + assert_(len(pol3) == i + j + 1, msg) + assert_almost_equal(val3, val1*val2, err_msg=msg) + + def test_lagdiv(self) : + for i in range(5) : + for j in range(5) : + msg = "At i=%d, j=%d" % (i,j) + ci = [0]*i + [1] + cj = [0]*j + [1] + tgt = lag.lagadd(ci, cj) + quo, rem = lag.lagdiv(tgt, ci) + res = lag.lagadd(lag.lagmul(quo, ci), rem) + assert_almost_equal(trim(res), trim(tgt), err_msg=msg) + + +class TestCalculus(TestCase) : + + def test_lagint(self) : + # check exceptions + assert_raises(ValueError, lag.lagint, [0], .5) + assert_raises(ValueError, lag.lagint, [0], -1) + assert_raises(ValueError, lag.lagint, [0], 1, [0,0]) + + # test integration of zero polynomial + for i in range(2, 5): + k = [0]*(i - 2) + [1] + res = lag.lagint([0], m=i, k=k) + assert_almost_equal(res, [1, -1]) + + # check single integration with integration constant + for i in range(5) : + scl = i + 1 + pol = [0]*i + [1] + tgt = [i] + [0]*i + [1/scl] + lagpol = lag.poly2lag(pol) + lagint = lag.lagint(lagpol, m=1, k=[i]) + res = lag.lag2poly(lagint) + assert_almost_equal(trim(res), trim(tgt)) + + # check single integration with integration constant and lbnd + for i in range(5) : + scl = i + 1 + pol = [0]*i + [1] + lagpol = lag.poly2lag(pol) + lagint = lag.lagint(lagpol, m=1, k=[i], lbnd=-1) + assert_almost_equal(lag.lagval(-1, lagint), i) + + # check single integration with integration constant and scaling + for i in range(5) : + scl = i + 1 + pol = [0]*i + [1] + tgt = [i] + [0]*i + [2/scl] + lagpol = lag.poly2lag(pol) + lagint = lag.lagint(lagpol, m=1, k=[i], scl=2) + res = lag.lag2poly(lagint) + assert_almost_equal(trim(res), trim(tgt)) + + # check multiple integrations with default k + for i in range(5) : + for j in range(2,5) : + pol = [0]*i + [1] + tgt = pol[:] + for k in range(j) : + tgt = lag.lagint(tgt, m=1) + res = lag.lagint(pol, m=j) + assert_almost_equal(trim(res), trim(tgt)) + + # check multiple integrations with defined k + for i in range(5) : + for j in range(2,5) : + pol = [0]*i + [1] + tgt = pol[:] + for k in range(j) : + tgt = lag.lagint(tgt, m=1, k=[k]) + res = lag.lagint(pol, m=j, k=range(j)) + assert_almost_equal(trim(res), trim(tgt)) + + # check multiple integrations with lbnd + for i in range(5) : + for j in range(2,5) : + pol = [0]*i + [1] + tgt = pol[:] + for k in range(j) : + tgt = lag.lagint(tgt, m=1, k=[k], lbnd=-1) + res = lag.lagint(pol, m=j, k=range(j), lbnd=-1) + assert_almost_equal(trim(res), trim(tgt)) + + # check multiple integrations with scaling + for i in range(5) : + for j in range(2,5) : + pol = [0]*i + [1] + tgt = pol[:] + for k in range(j) : + tgt = lag.lagint(tgt, m=1, k=[k], scl=2) + res = lag.lagint(pol, m=j, k=range(j), scl=2) + assert_almost_equal(trim(res), trim(tgt)) + + def test_lagder(self) : + # check exceptions + assert_raises(ValueError, lag.lagder, [0], .5) + assert_raises(ValueError, lag.lagder, [0], -1) + + # check that zeroth deriviative does nothing + for i in range(5) : + tgt = [1] + [0]*i + res = lag.lagder(tgt, m=0) + assert_equal(trim(res), trim(tgt)) + + # check that derivation is the inverse of integration + for i in range(5) : + for j in range(2,5) : + tgt = [1] + [0]*i + res = lag.lagder(lag.lagint(tgt, m=j), m=j) + assert_almost_equal(trim(res), trim(tgt)) + + # check derivation with scaling + for i in range(5) : + for j in range(2,5) : + tgt = [1] + [0]*i + res = lag.lagder(lag.lagint(tgt, m=j, scl=2), m=j, scl=.5) + assert_almost_equal(trim(res), trim(tgt)) + + +class TestMisc(TestCase) : + + def test_lagfromroots(self) : + res = lag.lagfromroots([]) + assert_almost_equal(trim(res), [1]) + for i in range(1,5) : + roots = np.cos(np.linspace(-np.pi, 0, 2*i + 1)[1::2]) + pol = lag.lagfromroots(roots) + res = lag.lagval(roots, pol) + tgt = 0 + assert_(len(pol) == i + 1) + assert_almost_equal(lag.lag2poly(pol)[-1], 1) + assert_almost_equal(res, tgt) + + def test_lagroots(self) : + assert_almost_equal(lag.lagroots([1]), []) + assert_almost_equal(lag.lagroots([0, 1]), [1]) + for i in range(2,5) : + tgt = np.linspace(0, 3, i) + res = lag.lagroots(lag.lagfromroots(tgt)) + assert_almost_equal(trim(res), trim(tgt)) + + def test_lagvander(self) : + # check for 1d x + x = np.arange(3) + v = lag.lagvander(x, 3) + assert_(v.shape == (3,4)) + for i in range(4) : + coef = [0]*i + [1] + assert_almost_equal(v[...,i], lag.lagval(x, coef)) + + # check for 2d x + x = np.array([[1,2],[3,4],[5,6]]) + v = lag.lagvander(x, 3) + assert_(v.shape == (3,2,4)) + for i in range(4) : + coef = [0]*i + [1] + assert_almost_equal(v[...,i], lag.lagval(x, coef)) + + def test_lagfit(self) : + def f(x) : + return x*(x - 1)*(x - 2) + + # Test exceptions + assert_raises(ValueError, lag.lagfit, [1], [1], -1) + assert_raises(TypeError, lag.lagfit, [[1]], [1], 0) + assert_raises(TypeError, lag.lagfit, [], [1], 0) + assert_raises(TypeError, lag.lagfit, [1], [[[1]]], 0) + assert_raises(TypeError, lag.lagfit, [1, 2], [1], 0) + assert_raises(TypeError, lag.lagfit, [1], [1, 2], 0) + assert_raises(TypeError, lag.lagfit, [1], [1], 0, w=[[1]]) + assert_raises(TypeError, lag.lagfit, [1], [1], 0, w=[1,1]) + + # Test fit + x = np.linspace(0,2) + y = f(x) + # + coef3 = lag.lagfit(x, y, 3) + assert_equal(len(coef3), 4) + assert_almost_equal(lag.lagval(x, coef3), y) + # + coef4 = lag.lagfit(x, y, 4) + assert_equal(len(coef4), 5) + assert_almost_equal(lag.lagval(x, coef4), y) + # + coef2d = lag.lagfit(x, np.array([y,y]).T, 3) + assert_almost_equal(coef2d, np.array([coef3,coef3]).T) + # test weighting + w = np.zeros_like(x) + yw = y.copy() + w[1::2] = 1 + y[0::2] = 0 + wcoef3 = lag.lagfit(x, yw, 3, w=w) + assert_almost_equal(wcoef3, coef3) + # + wcoef2d = lag.lagfit(x, np.array([yw,yw]).T, 3, w=w) + assert_almost_equal(wcoef2d, np.array([coef3,coef3]).T) + + def test_lagtrim(self) : + coef = [2, -1, 1, 0] + + # Test exceptions + assert_raises(ValueError, lag.lagtrim, coef, -1) + + # Test results + assert_equal(lag.lagtrim(coef), coef[:-1]) + assert_equal(lag.lagtrim(coef, 1), coef[:-3]) + assert_equal(lag.lagtrim(coef, 2), [0]) + + def test_lagline(self) : + assert_equal(lag.lagline(3,4), [7, -4]) + + def test_lag2poly(self) : + for i in range(7) : + assert_almost_equal(lag.lag2poly([0]*i + [1]), Llist[i]) + + def test_poly2lag(self) : + for i in range(7) : + assert_almost_equal(lag.poly2lag(Llist[i]), [0]*i + [1]) + + +def assert_poly_almost_equal(p1, p2): + assert_almost_equal(p1.coef, p2.coef) + assert_equal(p1.domain, p2.domain) + + +class TestLaguerreClass(TestCase) : + + p1 = lag.Laguerre([1,2,3]) + p2 = lag.Laguerre([1,2,3], [0,1]) + p3 = lag.Laguerre([1,2]) + p4 = lag.Laguerre([2,2,3]) + p5 = lag.Laguerre([3,2,3]) + + def test_equal(self) : + assert_(self.p1 == self.p1) + assert_(self.p2 == self.p2) + assert_(not self.p1 == self.p2) + assert_(not self.p1 == self.p3) + assert_(not self.p1 == [1,2,3]) + + def test_not_equal(self) : + assert_(not self.p1 != self.p1) + assert_(not self.p2 != self.p2) + assert_(self.p1 != self.p2) + assert_(self.p1 != self.p3) + assert_(self.p1 != [1,2,3]) + + def test_add(self) : + tgt = lag.Laguerre([2,4,6]) + assert_(self.p1 + self.p1 == tgt) + assert_(self.p1 + [1,2,3] == tgt) + assert_([1,2,3] + self.p1 == tgt) + + def test_sub(self) : + tgt = lag.Laguerre([1]) + assert_(self.p4 - self.p1 == tgt) + assert_(self.p4 - [1,2,3] == tgt) + assert_([2,2,3] - self.p1 == tgt) + + def test_mul(self) : + tgt = lag.Laguerre([ 14., -16., 56., -72., 54.]) + assert_poly_almost_equal(self.p1 * self.p1, tgt) + assert_poly_almost_equal(self.p1 * [1,2,3], tgt) + assert_poly_almost_equal([1,2,3] * self.p1, tgt) + + def test_floordiv(self) : + tgt = lag.Laguerre([1]) + assert_(self.p4 // self.p1 == tgt) + assert_(self.p4 // [1,2,3] == tgt) + assert_([2,2,3] // self.p1 == tgt) + + def test_mod(self) : + tgt = lag.Laguerre([1]) + assert_((self.p4 % self.p1) == tgt) + assert_((self.p4 % [1,2,3]) == tgt) + assert_(([2,2,3] % self.p1) == tgt) + + def test_divmod(self) : + tquo = lag.Laguerre([1]) + trem = lag.Laguerre([2]) + quo, rem = divmod(self.p5, self.p1) + assert_(quo == tquo and rem == trem) + quo, rem = divmod(self.p5, [1,2,3]) + assert_(quo == tquo and rem == trem) + quo, rem = divmod([3,2,3], self.p1) + assert_(quo == tquo and rem == trem) + + def test_pow(self) : + tgt = lag.Laguerre([1]) + for i in range(5) : + res = self.p1**i + assert_(res == tgt) + tgt = tgt*self.p1 + + def test_call(self) : + # domain = [0, 1] + x = np.linspace(0, 1) + tgt = 3*(.5*x**2 - 2*x + 1) + 2*(-x + 1) + 1 + assert_almost_equal(self.p1(x), tgt) + + # domain = [0, 1] + x = np.linspace(.5, 1) + xx = 2*x - 1 + assert_almost_equal(self.p2(x), self.p1(xx)) + + def test_degree(self) : + assert_equal(self.p1.degree(), 2) + + def test_cutdeg(self) : + assert_raises(ValueError, self.p1.cutdeg, .5) + assert_raises(ValueError, self.p1.cutdeg, -1) + assert_equal(len(self.p1.cutdeg(3)), 3) + assert_equal(len(self.p1.cutdeg(2)), 3) + assert_equal(len(self.p1.cutdeg(1)), 2) + assert_equal(len(self.p1.cutdeg(0)), 1) + + def test_convert(self) : + x = np.linspace(-1,1) + p = self.p1.convert(domain=[0,1]) + assert_almost_equal(p(x), self.p1(x)) + + def test_mapparms(self) : + parms = self.p2.mapparms() + assert_almost_equal(parms, [-1, 2]) + + def test_trim(self) : + coef = [1, 1e-6, 1e-12, 0] + p = lag.Laguerre(coef) + assert_equal(p.trim().coef, coef[:3]) + assert_equal(p.trim(1e-10).coef, coef[:2]) + assert_equal(p.trim(1e-5).coef, coef[:1]) + + def test_truncate(self) : + assert_raises(ValueError, self.p1.truncate, .5) + assert_raises(ValueError, self.p1.truncate, 0) + assert_equal(len(self.p1.truncate(4)), 3) + assert_equal(len(self.p1.truncate(3)), 3) + assert_equal(len(self.p1.truncate(2)), 2) + assert_equal(len(self.p1.truncate(1)), 1) + + def test_copy(self) : + p = self.p1.copy() + assert_(self.p1 == p) + + def test_integ(self) : + p = self.p2.integ() + assert_almost_equal(p.coef, lag.lagint([1,2,3], 1, 0, scl=.5)) + p = self.p2.integ(lbnd=0) + assert_almost_equal(p(0), 0) + p = self.p2.integ(1, 1) + assert_almost_equal(p.coef, lag.lagint([1,2,3], 1, 1, scl=.5)) + p = self.p2.integ(2, [1, 2]) + assert_almost_equal(p.coef, lag.lagint([1,2,3], 2, [1,2], scl=.5)) + + def test_deriv(self) : + p = self.p2.integ(2, [1, 2]) + assert_almost_equal(p.deriv(1).coef, self.p2.integ(1, [1]).coef) + assert_almost_equal(p.deriv(2).coef, self.p2.coef) + + def test_roots(self) : + p = lag.Laguerre(lag.poly2lag([0, -1, 0, 1]), [0, 1]) + res = p.roots() + tgt = [0, .5, 1] + assert_almost_equal(res, tgt) + + def test_linspace(self): + xdes = np.linspace(0, 1, 20) + ydes = self.p2(xdes) + xres, yres = self.p2.linspace(20) + assert_almost_equal(xres, xdes) + assert_almost_equal(yres, ydes) + + def test_fromroots(self) : + roots = [0, .5, 1] + p = lag.Laguerre.fromroots(roots, domain=[0, 1]) + res = p.coef + tgt = lag.poly2lag([0, -1, 0, 1]) + assert_almost_equal(res, tgt) + + def test_fit(self) : + def f(x) : + return x*(x - 1)*(x - 2) + x = np.linspace(0,3) + y = f(x) + + # test default value of domain + p = lag.Laguerre.fit(x, y, 3) + assert_almost_equal(p.domain, [0,3]) + + # test that fit works in given domains + p = lag.Laguerre.fit(x, y, 3, None) + assert_almost_equal(p(x), y) + assert_almost_equal(p.domain, [0,3]) + p = lag.Laguerre.fit(x, y, 3, []) + assert_almost_equal(p(x), y) + assert_almost_equal(p.domain, [-1, 1]) + # test that fit accepts weights. + w = np.zeros_like(x) + yw = y.copy() + w[1::2] = 1 + yw[0::2] = 0 + p = lag.Laguerre.fit(x, yw, 3, w=w) + assert_almost_equal(p(x), y) + + def test_identity(self) : + x = np.linspace(0,3) + p = lag.Laguerre.identity() + assert_almost_equal(p(x), x) + p = lag.Laguerre.identity([1,3]) + assert_almost_equal(p(x), x) +# + +if __name__ == "__main__": + run_module_suite() diff --git a/numpy/polynomial/tests/test_legendre.py b/numpy/polynomial/tests/test_legendre.py index f963bd2df..a35e6605e 100644 --- a/numpy/polynomial/tests/test_legendre.py +++ b/numpy/polynomial/tests/test_legendre.py @@ -429,7 +429,7 @@ class TestLegendreClass(TestCase) : def test_degree(self) : assert_equal(self.p1.degree(), 2) - def test_trimdeg(self) : + def test_cutdeg(self) : assert_raises(ValueError, self.p1.cutdeg, .5) assert_raises(ValueError, self.p1.cutdeg, -1) assert_equal(len(self.p1.cutdeg(3)), 3) @@ -531,3 +531,7 @@ class TestLegendreClass(TestCase) : assert_almost_equal(p(x), x) p = leg.Legendre.identity([1,3]) assert_almost_equal(p(x), x) +# + +if __name__ == "__main__": + run_module_suite() diff --git a/numpy/polynomial/tests/test_polynomial.py b/numpy/polynomial/tests/test_polynomial.py index 5890ac13f..4b93ea118 100644 --- a/numpy/polynomial/tests/test_polynomial.py +++ b/numpy/polynomial/tests/test_polynomial.py @@ -400,7 +400,7 @@ class TestPolynomialClass(TestCase) : def test_degree(self) : assert_equal(self.p1.degree(), 2) - def test_trimdeg(self) : + def test_cutdeg(self) : assert_raises(ValueError, self.p1.cutdeg, .5) assert_raises(ValueError, self.p1.cutdeg, -1) assert_equal(len(self.p1.cutdeg(3)), 3) @@ -502,3 +502,7 @@ class TestPolynomialClass(TestCase) : assert_almost_equal(p(x), x) p = poly.Polynomial.identity([1,3]) assert_almost_equal(p(x), x) +# + +if __name__ == "__main__": + run_module_suite() |