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.
x : array_like
Input values.
y : ndarray
The sign of x.
Examples
>>> np.sign([-5., 4.5]) array([-1., 1.]) >>> np.sign(0) 0
numpy.fabs
numpy.maximum