torch.sign
torch.sign(input, *, out=None) -> Tensor
Returns a new tensor with the signs of the elements of "input".
  \text{out}_{i} = \operatorname{sgn}(\text{input}_{i})

Parameters:
      input (Tensor) -- the input tensor.
Keyword Arguments:
      out (Tensor, optional) -- the output tensor.
Example:
  >>> a = torch.tensor([0.7, -1.2, 0., 2.3])
  >>> a
  tensor([ 0.7000, -1.2000,  0.0000,  2.3000])
  >>> torch.sign(a)
  tensor([ 1., -1.,  0.,  1.])
