PoissonNLLLoss
class torch.nn.PoissonNLLLoss(log_input=True, full=False, size_average=None, eps=1e-08, reduce=None, reduction='mean')
Negative log likelihood loss with Poisson distribution of target.
The loss can be described as:
  \text{target} \sim \mathrm{Poisson}(\text{input})
  \text{loss}(\text{input}, \text{target}) = \text{input} -
  \text{target} * \log(\text{input})                             +
  \log(\text{target!})

The last term can be omitted or approximated with Stirling formula.
   The approximation is used for target values more than 1. For
   targets less or equal to 1 zeros are added to the loss.
Parameters:
      * log_input (bool, optional) -- if "True" the loss is
        computed as \exp(\text{input}) - \text{target}\text{input},
        if "False" the loss is \text{input} -
        \text{target}\log(\text{input}+\text{eps}).
  * **full** (*bool**, **optional*) --
