mu_product in NAdam optimizer is never initialized #1154

The mu_product field in the NAdam state is never initialized and therefore defaults to zero. See here the initialization of the state (I also searched the rest of the code and there was no other initialization):

The mu_product by definition is always going to be the product of other multiplications, and therefore will always remain 0.

In the PyTorch documentation, you can see that in the source code for NAdam in the _init_group function they initialize the mu_product to 1: