chainer.functions.sign

chainer.functions.sign(x)

Elementwise sign function.

For a given input $x$, this function returns $sgn(x)$ defined as

$$\begin{split}sgn(x) = \left \{ \begin{array}{cc} -1 & {\rm if~x < 0} \\ 0 & {\rm if~x = 0} \\ 1 & {\rm if~x > 0} \\ \end{array} \right.\end{split}$$

Note

The gradient of this function is None everywhere and therefore unchains the computational graph.

Parameters

x (Variable or N-dimensional array) – Input variable for which the sign is computed.

Returns

Output variable.

Return type

Variable