diff options
Diffstat (limited to 'numpy/lib/ufunclike.py')
| -rw-r--r-- | numpy/lib/ufunclike.py | 85 |
1 files changed, 78 insertions, 7 deletions
diff --git a/numpy/lib/ufunclike.py b/numpy/lib/ufunclike.py index 6df529609..24f35da81 100644 --- a/numpy/lib/ufunclike.py +++ b/numpy/lib/ufunclike.py @@ -7,7 +7,38 @@ __all__ = ['fix', 'isneginf', 'isposinf', 'log2'] import numpy.core.numeric as nx def fix(x, y=None): - """ Round x to nearest integer towards zero. + """ + Round to nearest integer towards zero. + + Round an array of floats element-wise to nearest integer towards zero. + The rounded values are returned as floats. + + Parameters + ---------- + x : array_like + An array of floats to be rounded + y : ndarray, optional + Output array + + Returns + ------- + out : ndarray of floats + The array of rounded numbers + + See Also + -------- + floor : Round downwards + around : Round to given number of decimals + + Examples + -------- + >>> np.fix(3.14) + 3.0 + >>> np.fix(3) + 3.0 + >>> np.fix([2.1, 2.9, -2.1, -2.9]) + array([ 2., 2., -2., -2.]) + """ x = nx.asanyarray(x) if y is None: @@ -19,7 +50,10 @@ def fix(x, y=None): def isposinf(x, y=None): """ - Return True where x is +infinity, and False otherwise. + Shows which elements of the input are positive infinity. + + Returns a numpy array resulting from an element-wise test for positive + infinity. Parameters ---------- @@ -31,16 +65,54 @@ def isposinf(x, y=None): Returns ------- y : ndarray - A boolean array where y[i] = True only if x[i] = +Inf. + A numpy boolean array with the same dimensions as the input. + If second argument is not supplied then a numpy boolean array is returned + with values True where the corresponding element of the input is positive + infinity and values False where the element of the input is not positive + infinity. + + If second argument is supplied then an numpy integer array is returned + with values 1 where the corresponding element of the input is positive + positive infinity. See Also -------- - isneginf, isfinite + isinf : Shows which elements are negative or positive infinity. + isneginf : Shows which elements are negative infinity. + isnan : Shows which elements are Not a Number (NaN). + isfinite: Shows which elements are not: Not a number, positive and + negative infinity + + Notes + ----- + Numpy uses the IEEE Standard for Binary Floating-Point for Arithmetic + (IEEE 754). This means that Not a Number is not equivalent to infinity. + Also that positive infinity is not equivalent to negative infinity. But + infinity is equivalent to positive infinity. + + Errors result if second argument is also supplied with scalar input or + if first and second arguments have different shapes. + + Numpy's definitions for positive infinity (PINF) and negative infinity + (NINF) may be change in the future versions. + Examples -------- + >>> np.isposinf(np.PINF) + array(True, dtype=bool) + >>> np.isposinf(np.inf) + array(True, dtype=bool) + >>> np.isposinf(np.NINF) + array(False, dtype=bool) >>> np.isposinf([-np.inf, 0., np.inf]) - array([ False, False, True], dtype=bool) + array([False, False, True], dtype=bool) + >>> x=np.array([-np.inf, 0., np.inf]) + >>> y=np.array([2,2,2]) + >>> np.isposinf(x,y) + array([1, 0, 0]) + >>> y + array([1, 0, 0]) """ if y is None: @@ -95,11 +167,10 @@ def log2(x, y=None): Returns ------- - y : {ndarray, scalar} + y : ndarray The logarithm to the base 2 of `x` elementwise. NaNs are returned where `x` is negative. - See Also -------- log, log1p, log10 |