torch.log2
torch.log2(input, *, out=None) -> Tensor
Returns a new tensor with the logarithm to the base 2 of the
   elements of "input".
  y_{i} = \log_{2} (x_{i})

Parameters:
      input (Tensor) -- the input tensor.
Keyword Arguments:
      out (Tensor, optional) -- the output tensor.
Example:
  >>> a = torch.rand(5)
  >>> a
  tensor([ 0.8419,  0.8003,  0.9971,  0.5287,  0.0490])


  >>> torch.log2(a)
  tensor([-0.2483, -0.3213, -0.0042, -0.9196, -4.3504])
