For complex tensors, this function returns a new tensor whose elemants have the same angle as that of the
elements of input and absolute value 1. For a non-complex tensor, this function
returns the signs of the elements of input (see torch_sign).
\(\mbox{out}_{i} = 0\), if \(|{\mbox{{input}}_i}| == 0\)
\(\mbox{out}_{i} = \frac{{\mbox{{input}}_i}}{|{\mbox{{input}}_i}|}\), otherwise