# mars.tensor.sign#

mars.tensor.sign(x, out=None, where=None, **kwargs)[source]#

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 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.

• out (Tensor, None, or tuple of Tensor and None, optional) – A location into which the result is stored. If provided, it must have a shape that the inputs broadcast to. If not provided or None, a freshly-allocated tensor is returned. A tuple (possible only as a keyword argument) must have length equal to the number of outputs.

• where (array_like, optional) – Values of True indicate to calculate the ufunc at that position, values of False indicate to leave the value in the output alone.

• **kwargs

Returns

y – The sign of x.

Return type

Tensor

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

>>> import mars.tensor as mt

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