diff options
Diffstat (limited to 'numpy/lib/ufunclike.py')
| -rw-r--r-- | numpy/lib/ufunclike.py | 94 |
1 files changed, 59 insertions, 35 deletions
diff --git a/numpy/lib/ufunclike.py b/numpy/lib/ufunclike.py index 8ea7c6662..5dbc3f225 100644 --- a/numpy/lib/ufunclike.py +++ b/numpy/lib/ufunclike.py @@ -27,7 +27,7 @@ def fix(x, y=None): See Also -------- - floor : Round downwards + trunc, floor, ceil around : Round to given number of decimals Examples @@ -50,48 +50,40 @@ def fix(x, y=None): def isposinf(x, y=None): """ - Shows which elements of the input are positive infinity. - - Returns a numpy array resulting from an element-wise test for positive - infinity. + Test element-wise for positive infinity, return result as bool array. Parameters ---------- x : array_like - The input array. - y : array_like - A boolean array with the same shape as `x` to store the result. + The input array. + y : array_like, optional + A boolean array with the same shape as `x` to store the result. Returns ------- y : ndarray - 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. + A boolean array with the same dimensions as the input. + If second argument is not supplied then a 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. + If a second argument is supplied the result is stored there. If the + type of that array is a numeric type the result is represented as zeros + and ones, if the type is boolean then as False and True. + The return value `y` is then a reference to that array. See Also -------- - 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 + isinf, isneginf, isfinite, isnan 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. + (IEEE 754). - Errors result if second argument is also supplied with scalar input or - if first and second arguments have different shapes. + Errors result if the second argument is also supplied when `x` is a + scalar input, or if first and second arguments have different shapes. Examples -------- @@ -103,9 +95,10 @@ def isposinf(x, y=None): array(False, dtype=bool) >>> np.isposinf([-np.inf, 0., np.inf]) array([False, False, True], dtype=bool) - >>> x=np.array([-np.inf, 0., np.inf]) - >>> y=np.array([2,2,2]) - >>> np.isposinf(x,y) + + >>> 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]) @@ -119,29 +112,60 @@ def isposinf(x, y=None): def isneginf(x, y=None): """ - Return True where x is -infinity, and False otherwise. + Test element-wise for negative infinity, return result as bool array. Parameters ---------- x : array_like - The input array. - y : array_like - A boolean array with the same shape as `x` to store the result. + The input array. + y : array_like, optional + A boolean array with the same shape and type as `x` to store the + result. Returns ------- y : ndarray - A boolean array where y[i] = True only if x[i] = -Inf. + A 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 negative infinity and values False where the element of + the input is not negative infinity. + + If a second argument is supplied the result is stored there. If the + type of that array is a numeric type the result is represented as + zeros and ones, if the type is boolean then as False and True. The + return value `y` is then a reference to that array. See Also -------- - isposinf, isfinite + isinf, isposinf, isnan, isfinite + + Notes + ----- + Numpy uses the IEEE Standard for Binary Floating-Point for Arithmetic + (IEEE 754). + + Errors result if the second argument is also supplied when x is a scalar + input, or if first and second arguments have different shapes. Examples -------- + >>> np.isneginf(np.NINF) + array(True, dtype=bool) + >>> np.isneginf(np.inf) + array(False, dtype=bool) + >>> np.isneginf(np.PINF) + array(False, dtype=bool) >>> np.isneginf([-np.inf, 0., np.inf]) array([ True, False, False], dtype=bool) + >>> x = np.array([-np.inf, 0., np.inf]) + >>> y = np.array([2, 2, 2]) + >>> np.isneginf(x, y) + array([1, 0, 0]) + >>> y + array([1, 0, 0]) + """ if y is None: x = nx.asarray(x) |