torch.sgn
torch.sgn(input, *, out=None) -> Tensor
This function is an extension of torch.sign() to complex tensors.
   It computes a new tensor whose elements have the same angles as the
   corresponding elements of "input" and absolute values (i.e.
   magnitudes) of one for complex tensors and is equivalent to
   torch.sign() for non-complex tensors.
  \text{out}_{i} = \begin{cases}                 0 &
  |\text{{input}}_i| == 0 \\
  \frac{{\text{{input}}_i}}{|{\text{{input}}_i}|} &
  \text{otherwise}                 \end{cases}

Parameters:
      input (Tensor) -- the input tensor.
Keyword Arguments:
      out (Tensor, optional) -- the output tensor.
Example:
  >>> t = torch.tensor([3+4j, 7-24j, 0, 1+2j])
  >>> t.sgn()
  tensor([0.6000+0.8000j, 0.2800-0.9600j, 0.0000+0.0000j, 0.4472+0.8944j])
