numpy.sign¶
-
numpy.
sign
(x[, out]) = <ufunc 'sign'>¶ Returns an element-wise indication of the sign of a number.
The
sign
function returns-1 if x < 0, 0 if x==0, 1 if x > 0
. nan is returned for nan inputs.For complex inputs, the
sign
function returnssign(x.real) + 0j if x.real != 0 else sign(x.imag) + 0j
.complex(nan, 0) is returned for complex nan inputs.
Parameters: x : array_like
Input values.
Returns: y : ndarray
The sign of x.
Notes
There is more than one definition of sign in common use for complex numbers. The definition used here is equivalent to
which is different from a common alternative,
.
Examples
>>> np.sign([-5., 4.5]) array([-1., 1.]) >>> np.sign(0) 0 >>> np.sign(5-2j) (1+0j)