torch.nn.functional.log_softmax
torch.nn.functional.log_softmax(input, dim=None, _stacklevel=3, dtype=None)
Applies a softmax followed by a logarithm.
While mathematically equivalent to log(softmax(x)), doing these two
   operations separately is slower and numerically unstable. This
   function uses an alternative formulation to compute the output and
   gradient correctly.
See "LogSoftmax" for more details.
Parameters:
      * input (Tensor) -- input
  * **dim** (*int*) -- A dimension along which log_softmax will be
    computed.

  * **dtype** ("torch.dtype", optional) -- the desired data type
    of returned tensor. If specified, the input tensor is cast to
    "dtype" before the operation is performed. This is useful for
    preventing data type overflows. Default: None.

Return type:
      Tensor