torch.log1p
torch.log1p(input, *, out=None) -> Tensor
Returns a new tensor with the natural logarithm of (1 + "input").
  y_i = \log_{e} (x_i + 1)

Note:
 This function is more accurate than "torch.log()" for small
 values of "input"

Parameters:
      input (Tensor) -- the input tensor.
Keyword Arguments:
      out (Tensor, optional) -- the output tensor.
Example:
  >>> a = torch.randn(5)
  >>> a
  tensor([-1.0090, -0.9923,  1.0249, -0.5372,  0.2492])
  >>> torch.log1p(a)
  tensor([    nan, -4.8653,  0.7055, -0.7705,  0.2225])
