jax.numpy.sign

jax.numpy.sign(x)[source]

Returns an element-wise indication of the sign of a number.

LAX-backend implementation of sign(). Original docstring below.

sign(x, /, out=None, *, where=True, casting=’same_kind’, order=’K’, dtype=None, subok=True[, signature, extobj])

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 returns sign(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 – The sign of x. This is a scalar if x is a scalar.

Return type

ndarray

Notes

There is more than one definition of sign in common use for complex numbers. The definition used here is equivalent to \(x/\sqrt{x*x}\) which is different from a common alternative, \(x/|x|\).

Examples

>>> np.sign([-5., 4.5])
array([-1.,  1.])
>>> np.sign(0)
0
>>> np.sign(5-2j)
(1+0j)