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author | Travis Oliphant <oliphant@enthought.com> | 2005-12-25 09:49:16 +0000 |
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committer | Travis Oliphant <oliphant@enthought.com> | 2005-12-25 09:49:16 +0000 |
commit | 25ddd8d255ecc33d6c5a8b1d0a428ac8961987f7 (patch) | |
tree | f2eb0534b8baacb35ecff5af7bf5d1b2ad073c12 /scipy/basic/linalg.py | |
parent | 495a683a59ffd2b20769d33e6eb24ff9101bc50a (diff) | |
download | numpy-25ddd8d255ecc33d6c5a8b1d0a428ac8961987f7.tar.gz |
Moving out basic tools to higher level.
Diffstat (limited to 'scipy/basic/linalg.py')
-rw-r--r-- | scipy/basic/linalg.py | 549 |
1 files changed, 0 insertions, 549 deletions
diff --git a/scipy/basic/linalg.py b/scipy/basic/linalg.py deleted file mode 100644 index a669b27c4..000000000 --- a/scipy/basic/linalg.py +++ /dev/null @@ -1,549 +0,0 @@ -"""Lite version of scipy.linalg. -""" -# This module is a lite version of LinAlg.py module which contains -# high-level Python interface to the LAPACK library. The lite version -# only accesses the following LAPACK functions: dgesv, zgesv, dgeev, -# zgeev, dgesdd, zgesdd, dgelsd, zgelsd, dsyevd, zheevd, dgetrf, dpotrf. - -from scipy.base import * -import lapack_lite -import math - -# Error object -class LinAlgError(Exception): - pass - -# Helper routines -_lapack_type = {'f': 0, 'd': 1, 'F': 2, 'D': 3} -_lapack_letter = ['s', 'd', 'c', 'z'] -_array_kind = {'i':0, 'l': 0, 'f': 0, 'd': 0, 'F': 1, 'D': 1} -_array_precision = {'i': 1, 'l': 1, 'f': 0, 'd': 1, 'F': 0, 'D': 1} -_array_type = [['f', 'd'], ['F', 'D']] - -def _commonType(*arrays): - kind = 0 -# precision = 0 -# force higher precision in lite version - precision = 1 - for a in arrays: - t = a.dtypechar - kind = max(kind, _array_kind[t]) - precision = max(precision, _array_precision[t]) - return _array_type[kind][precision] - -def _castCopyAndTranspose(type, *arrays): - cast_arrays = () - for a in arrays: - cast_arrays = cast_arrays + (transpose(a).astype(type),) - if len(cast_arrays) == 1: - return cast_arrays[0] - else: - return cast_arrays - -# _fastCopyAndTranpose is an optimized version of _castCopyAndTranspose. -# It assumes the input is 2D (as all the calls in here are). - -_fastCT = fastCopyAndTranspose - -def _fastCopyAndTranspose(type, *arrays): - cast_arrays = () - for a in arrays: - if a.dtypechar == type: - cast_arrays = cast_arrays + (_fastCT(a),) - else: - cast_arrays = cast_arrays + (_fastCT(a.astype(type)),) - if len(cast_arrays) == 1: - return cast_arrays[0] - else: - return cast_arrays - -def _assertRank2(*arrays): - for a in arrays: - if len(a.shape) != 2: - raise LinAlgError, 'Array must be two-dimensional' - -def _assertSquareness(*arrays): - for a in arrays: - if max(a.shape) != min(a.shape): - raise LinAlgError, 'Array must be square' - - -# Linear equations - -def solve_linear_equations(a, b): - one_eq = len(b.shape) == 1 - if one_eq: - b = b[:, NewAxis] - _assertRank2(a, b) - _assertSquareness(a) - n_eq = a.shape[0] - n_rhs = b.shape[1] - if n_eq != b.shape[0]: - raise LinAlgError, 'Incompatible dimensions' - t =_commonType(a, b) -# lapack_routine = _findLapackRoutine('gesv', t) - if _array_kind[t] == 1: # Complex routines take different arguments - lapack_routine = lapack_lite.zgesv - else: - lapack_routine = lapack_lite.dgesv - a, b = _fastCopyAndTranspose(t, a, b) - pivots = zeros(n_eq, 'i') - results = lapack_routine(n_eq, n_rhs, a, n_eq, pivots, b, n_eq, 0) - if results['info'] > 0: - raise LinAlgError, 'Singular matrix' - if one_eq: - return ravel(b) # I see no need to copy here - else: - return transpose(b) # no need to copy - - -# Matrix inversion - -def inverse(a): - return solve_linear_equations(a, identity(a.shape[0])) - - -# Cholesky decomposition - -def cholesky_decomposition(a): - _assertRank2(a) - _assertSquareness(a) - t =_commonType(a) - a = _castCopyAndTranspose(t, a) - m = a.shape[0] - n = a.shape[1] - if _array_kind[t] == 1: - lapack_routine = lapack_lite.zpotrf - else: - lapack_routine = lapack_lite.dpotrf - results = lapack_routine('L', n, a, m, 0) - if results['info'] > 0: - raise LinAlgError, 'Matrix is not positive definite - Cholesky decomposition cannot be computed' - return transpose(triu(a,k=0)).copy() - - -# Eigenvalues - -def eigenvalues(a): - _assertRank2(a) - _assertSquareness(a) - t =_commonType(a) - real_t = _array_type[0][_array_precision[t]] - a = _fastCopyAndTranspose(t, a) - n = a.shape[0] - dummy = zeros((1,), t) - if _array_kind[t] == 1: # Complex routines take different arguments - lapack_routine = lapack_lite.zgeev - w = zeros((n,), t) - rwork = zeros((n,),real_t) - lwork = 1 - work = zeros((lwork,), t) - results = lapack_routine('N', 'N', n, a, n, w, - dummy, 1, dummy, 1, work, -1, rwork, 0) - lwork = int(abs(work[0])) - work = zeros((lwork,), t) - results = lapack_routine('N', 'N', n, a, n, w, - dummy, 1, dummy, 1, work, lwork, rwork, 0) - else: - lapack_routine = lapack_lite.dgeev - wr = zeros((n,), t) - wi = zeros((n,), t) - lwork = 1 - work = zeros((lwork,), t) - results = lapack_routine('N', 'N', n, a, n, wr, wi, - dummy, 1, dummy, 1, work, -1, 0) - lwork = int(work[0]) - work = zeros((lwork,), t) - results = lapack_routine('N', 'N', n, a, n, wr, wi, - dummy, 1, dummy, 1, work, lwork, 0) - if logical_and.reduce(equal(wi, 0.)): - w = wr - else: - w = wr+1j*wi - if results['info'] > 0: - raise LinAlgError, 'Eigenvalues did not converge' - return w - - -def Heigenvalues(a, UPLO='L'): - _assertRank2(a) - _assertSquareness(a) - t =_commonType(a) - real_t = _array_type[0][_array_precision[t]] - a = _castCopyAndTranspose(t, a) - n = a.shape[0] - liwork = 5*n+3 - iwork = zeros((liwork,),'i') - if _array_kind[t] == 1: # Complex routines take different arguments - lapack_routine = lapack_lite.zheevd - w = zeros((n,), real_t) - lwork = 1 - work = zeros((lwork,), t) - lrwork = 1 - rwork = zeros((lrwork,),real_t) - results = lapack_routine('N', UPLO, n, a, n,w, work, -1, rwork, -1, iwork, liwork, 0) - lwork = int(abs(work[0])) - work = zeros((lwork,), t) - lrwork = int(rwork[0]) - rwork = zeros((lrwork,),real_t) - results = lapack_routine('N', UPLO, n, a, n,w, work, lwork, rwork, lrwork, iwork, liwork, 0) - else: - lapack_routine = lapack_lite.dsyevd - w = zeros((n,), t) - lwork = 1 - work = zeros((lwork,), t) - results = lapack_routine('N', UPLO, n, a, n,w, work, -1, iwork, liwork, 0) - lwork = int(work[0]) - work = zeros((lwork,), t) - results = lapack_routine('N', UPLO, n, a, n,w, work, lwork, iwork, liwork, 0) - if results['info'] > 0: - raise LinAlgError, 'Eigenvalues did not converge' - return w - -def _convertarray(a): - if issubclass(a.dtype, complexfloating): - if a.dtypechar == 'D': - a = _fastCT(a) - else: - a = _fastCT(a.astype('D')) - else: - if a.dtypechar == 'd': - a = _fastCT(a) - else: - a = _fastCT(a.astype('d')) - return a, a.dtypechar - -# Eigenvectors - -def eig(a): - """eig(a) returns u,v where u is the eigenvalues and -v is a matrix of eigenvectors with vector v[:,i] corresponds to -eigenvalue u[i]. Satisfies the equation dot(a, v[:,i]) = u[i]*v[:,i] -""" - a = asarray(a) - _assertRank2(a) - _assertSquareness(a) - a,t = _convertarray(a) # convert to float_ or complex_ type - wrap = a.__array_wrap__ - real_t = 'd' - n = a.shape[0] - dummy = zeros((1,), t) - if t == 'D': # Complex routines take different arguments - lapack_routine = lapack_lite.zgeev - w = zeros((n,), t) - v = zeros((n,n), t) - lwork = 1 - work = zeros((lwork,),t) - rwork = zeros((2*n,),real_t) - results = lapack_routine('N', 'V', n, a, n, w, - dummy, 1, v, n, work, -1, rwork, 0) - lwork = int(abs(work[0])) - work = zeros((lwork,),t) - results = lapack_routine('N', 'V', n, a, n, w, - dummy, 1, v, n, work, lwork, rwork, 0) - else: - lapack_routine = lapack_lite.dgeev - wr = zeros((n,), t) - wi = zeros((n,), t) - vr = zeros((n,n), t) - lwork = 1 - work = zeros((lwork,),t) - results = lapack_routine('N', 'V', n, a, n, wr, wi, - dummy, 1, vr, n, work, -1, 0) - lwork = int(work[0]) - work = zeros((lwork,),t) - results = lapack_routine('N', 'V', n, a, n, wr, wi, - dummy, 1, vr, n, work, lwork, 0) - if logical_and.reduce(equal(wi, 0.)): - w = wr - v = vr - else: - w = wr+1j*wi - v = array(vr,Complex) - ind = nonzero( - equal( - equal(wi,0.0) # true for real e-vals - ,0) # true for complex e-vals - ) # indices of complex e-vals - for i in range(len(ind)/2): - v[ind[2*i]] = vr[ind[2*i]] + 1j*vr[ind[2*i+1]] - v[ind[2*i+1]] = vr[ind[2*i]] - 1j*vr[ind[2*i+1]] - if results['info'] > 0: - raise LinAlgError, 'Eigenvalues did not converge' - return w,wrap(v.transpose()) - - -def eigh(a, UPLO='L'): - _assertRank2(a) - _assertSquareness(a) - t =_commonType(a) - real_t = _array_type[0][_array_precision[t]] - a = _castCopyAndTranspose(t, a) - wrap = a.__array_wrap__ - n = a.shape[0] - liwork = 5*n+3 - iwork = zeros((liwork,),'i') - if _array_kind[t] == 1: # Complex routines take different arguments - lapack_routine = lapack_lite.zheevd - w = zeros((n,), real_t) - lwork = 1 - work = zeros((lwork,), t) - lrwork = 1 - rwork = zeros((lrwork,),real_t) - results = lapack_routine('V', UPLO, n, a, n,w, work, -1, rwork, -1, iwork, liwork, 0) - lwork = int(abs(work[0])) - work = zeros((lwork,), t) - lrwork = int(rwork[0]) - rwork = zeros((lrwork,),real_t) - results = lapack_routine('V', UPLO, n, a, n,w, work, lwork, rwork, lrwork, iwork, liwork, 0) - else: - lapack_routine = lapack_lite.dsyevd - w = zeros((n,), t) - lwork = 1 - work = zeros((lwork,),t) - results = lapack_routine('V', UPLO, n, a, n,w, work, -1, iwork, liwork, 0) - lwork = int(work[0]) - work = zeros((lwork,),t) - results = lapack_routine('V', UPLO, n, a, n,w, work, lwork, iwork, liwork, 0) - if results['info'] > 0: - raise LinAlgError, 'Eigenvalues did not converge' - return w,wrap(a.transpose()) - - -# Singular value decomposition - -def svd(a, full_matrices = 1): - _assertRank2(a) - n = a.shape[1] - m = a.shape[0] - t =_commonType(a) - real_t = _array_type[0][_array_precision[t]] - a = _fastCopyAndTranspose(t, a) - wrap = a.__array_wrap__ - if full_matrices: - nu = m - nvt = n - option = 'A' - else: - nu = min(n,m) - nvt = min(n,m) - option = 'S' - s = zeros((min(n,m),), real_t) - u = zeros((nu, m), t) - vt = zeros((n, nvt), t) - iwork = zeros((8*min(m,n),), 'i') - if _array_kind[t] == 1: # Complex routines take different arguments - lapack_routine = lapack_lite.zgesdd - rwork = zeros((5*min(m,n)*min(m,n) + 5*min(m,n),), real_t) - lwork = 1 - work = zeros((lwork,), t) - results = lapack_routine(option, m, n, a, m, s, u, m, vt, nvt, - work, -1, rwork, iwork, 0) - lwork = int(abs(work[0])) - work = zeros((lwork,), t) - results = lapack_routine(option, m, n, a, m, s, u, m, vt, nvt, - work, lwork, rwork, iwork, 0) - else: - lapack_routine = lapack_lite.dgesdd - lwork = 1 - work = zeros((lwork,), t) - results = lapack_routine(option, m, n, a, m, s, u, m, vt, nvt, - work, -1, iwork, 0) - lwork = int(work[0]) - work = zeros((lwork,), t) - results = lapack_routine(option, m, n, a, m, s, u, m, vt, nvt, - work, lwork, iwork, 0) - if results['info'] > 0: - raise LinAlgError, 'SVD did not converge' - return wrap(transpose(u)), s, \ - wrap(transpose(vt)) # why copy here? - - -# Generalized inverse - -def generalized_inverse(a, rcond = 1.e-10): - a = array(a, copy=0) - if a.dtypechar in typecodes['Complex']: - a = conjugate(a) - u, s, vt = svd(a, 0) - m = u.shape[0] - n = vt.shape[1] - cutoff = rcond*maximum.reduce(s) - for i in range(min(n,m)): - if s[i] > cutoff: - s[i] = 1./s[i] - else: - s[i] = 0.; - wrap = a.__array_wrap__ - return wrap(dot(transpose(vt), - multiply(s[:, NewAxis],transpose(u)))) - -# Determinant - -def determinant(a): - _assertRank2(a) - _assertSquareness(a) - t =_commonType(a) - a = _fastCopyAndTranspose(t, a) - n = a.shape[0] - if _array_kind[t] == 1: - lapack_routine = lapack_lite.zgetrf - else: - lapack_routine = lapack_lite.dgetrf - pivots = zeros((n,), 'i') - results = lapack_routine(n, n, a, n, pivots, 0) - sign = add.reduce(not_equal(pivots, - arrayrange(1, n+1))) % 2 - return (1.-2.*sign)*multiply.reduce(diagonal(a),axis=-1) - -# Linear Least Squares - -def linear_least_squares(a, b, rcond=1.e-10): - """returns x,resids,rank,s -where x minimizes 2-norm(|b - Ax|) - resids is the sum square residuals - rank is the rank of A - s is the rank of the singular values of A in descending order - -If b is a matrix then x is also a matrix with corresponding columns. -If the rank of A is less than the number of columns of A or greater than -the number of rows, then residuals will be returned as an empty array -otherwise resids = sum((b-dot(A,x)**2). -Singular values less than s[0]*rcond are treated as zero. -""" - a = asarray(a) - b = asarray(b) - one_eq = len(b.shape) == 1 - if one_eq: - b = b[:, NewAxis] - _assertRank2(a, b) - m = a.shape[0] - n = a.shape[1] - n_rhs = b.shape[1] - ldb = max(n,m) - if m != b.shape[0]: - raise LinAlgError, 'Incompatible dimensions' - t =_commonType(a, b) - real_t = _array_type[0][_array_precision[t]] - bstar = zeros((ldb,n_rhs),t) - bstar[:b.shape[0],:n_rhs] = b.copy() - a,bstar = _castCopyAndTranspose(t, a, bstar) - s = zeros((min(m,n),),real_t) - nlvl = max( 0, int( math.log( float(min( m,n ))/2. ) ) + 1 ) - iwork = zeros((3*min(m,n)*nlvl+11*min(m,n),), 'i') - if _array_kind[t] == 1: # Complex routines take different arguments - lapack_routine = lapack_lite.zgelsd - lwork = 1 - rwork = zeros((lwork,), real_t) - work = zeros((lwork,),t) - results = lapack_routine( m, n, n_rhs, a, m, bstar,ldb , s, rcond, - 0,work,-1,rwork,iwork,0 ) - lwork = int(abs(work[0])) - rwork = zeros((lwork,),real_t) - a_real = zeros((m,n),real_t) - bstar_real = zeros((ldb,n_rhs,),real_t) - results = lapack_lite.dgelsd( m, n, n_rhs, a_real, m, bstar_real,ldb , s, rcond, - 0,rwork,-1,iwork,0 ) - lrwork = int(rwork[0]) - work = zeros((lwork,), t) - rwork = zeros((lrwork,), real_t) - results = lapack_routine( m, n, n_rhs, a, m, bstar,ldb , s, rcond, - 0,work,lwork,rwork,iwork,0 ) - else: - lapack_routine = lapack_lite.dgelsd - lwork = 1 - work = zeros((lwork,), t) - results = lapack_routine( m, n, n_rhs, a, m, bstar,ldb , s, rcond, - 0,work,-1,iwork,0 ) - lwork = int(work[0]) - work = zeros((lwork,), t) - results = lapack_routine( m, n, n_rhs, a, m, bstar,ldb , s, rcond, - 0,work,lwork,iwork,0 ) - if results['info'] > 0: - raise LinAlgError, 'SVD did not converge in Linear Least Squares' - resids = array([],t) - if one_eq: - x = ravel(bstar)[:n].copy() - if (results['rank']==n) and (m>n): - resids = array([sum((ravel(bstar)[n:])**2)]) - else: - x = transpose(bstar)[:n,:].copy() - if (results['rank']==n) and (m>n): - resids = sum((transpose(bstar)[n:,:])**2).copy() - return x,resids,results['rank'],s[:min(n,m)].copy() - -def singular_value_decomposition(A, full_matrices=0): - return svd(A, 0) - -def eigenvectors(A): - w, v = eig(A) - return w, transpose(v) - -def Heigenvectors(A): - w, v = eigh(A) - return w, transpose(v) - -inv = inverse -solve = solve_linear_equations -cholesky = cholesky_decomposition -eigvals = eigenvalues -eigvalsh = Heigenvalues -pinv = generalized_inverse -det = determinant -lstsq = linear_least_squares - -if __name__ == '__main__': - def test(a, b): - - print "All numbers printed should be (almost) zero:" - - x = solve_linear_equations(a, b) - check = b - matrixmultiply(a, x) - print check - - - a_inv = inverse(a) - check = matrixmultiply(a, a_inv)-identity(a.shape[0]) - print check - - - ev = eigenvalues(a) - - evalues, evectors = eig(a) - check = ev-evalues - print check - - evectors = transpose(evectors) - check = matrixmultiply(a, evectors)-evectors*evalues - print check - - - u, s, vt = svd(a,0) - check = a - matrixmultiply(u*s, vt) - print check - - - a_ginv = generalized_inverse(a) - check = matrixmultiply(a, a_ginv)-identity(a.shape[0]) - print check - - - det = determinant(a) - check = det-multiply.reduce(evalues) - print check - - x, residuals, rank, sv = linear_least_squares(a, b) - check = b - matrixmultiply(a, x) - print check - print rank-a.shape[0] - print sv-s - - a = array([[1.,2.], [3.,4.]]) - b = array([2., 1.]) - test(a, b) - - a = a+0j - b = b+0j - test(a, b) - - |