numpy.sign — NumPy v1.11 Manual (original) (raw)
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)