jax.numpy.sign

jax.numpy.sign(x, /)

Return an element-wise indication of sign of the input.

JAX implementation of numpy.sign.

The sign of x for real-valued input is:

\[\begin{split}\mathrm{sign}(x) = \begin{cases} 1, & x > 0\\ 0, & x = 0\\ -1, & x < 0 \end{cases}\end{split}\]

For complex valued input, jnp.sign returns a unit vector representing the phase. For generalized case, the sign of x is given by:

\[\begin{split}\mathrm{sign}(x) = \begin{cases} \frac{x}{abs(x)}, & x \ne 0\\ 0, & x = 0 \end{cases}\end{split}\]

Parameters:

x (ArrayLike) – input array or scalar.

Returns:

An array with same shape and dtype as x containing the sign indication.

Return type:

Array

See also

• jax.numpy.positive(): Returns element-wise positive values of the input.

• jax.numpy.negative(): Returns element-wise negative values of the input.

Examples

For Real-valued inputs:

>>> x = jnp.array([0., -3., 7.])
>>> jnp.sign(x)
Array([ 0., -1.,  1.], dtype=float32)

For complex-inputs:

>>> x1 = jnp.array([1, 3+4j, 5j])
>>> jnp.sign(x1)
Array([1. +0.j , 0.6+0.8j, 0. +1.j ], dtype=complex64)