Log_softmax — nnf_log_softmax • torch

Applies a softmax followed by a logarithm.

nnf_log_softmax(input, dim = NULL, dtype = NULL)

Arguments

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 casted to `dtype` before the operation is performed. This is useful for preventing data type overflows. Default: `NULL`.

Details

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.