torch.atanh
torch.atanh(input, *, out=None) -> Tensor
Returns a new tensor with the inverse hyperbolic tangent of the
   elements of "input".
Note:
 The domain of the inverse hyperbolic tangent is *(-1, 1)* and
 values outside this range will be mapped to "NaN", except for the
 values *1* and *-1* for which the output is mapped to *+/-INF*
 respectively.

  \text{out}_{i} = \tanh^{-1}(\text{input}_{i})

Parameters:
      input (Tensor) -- the input tensor.
Keyword Arguments:
      out (Tensor, optional) -- the output tensor.
Example:
  >>> a = torch.randn(4).uniform_(-1, 1)
  >>> a
  tensor([ -0.9385, 0.2968, -0.8591, -0.1871 ])
  >>> torch.atanh(a)
  tensor([ -1.7253, 0.3060, -1.2899, -0.1893 ])
