Fix nimarb#23: Improve calc_loss's numerical stability using cross entropy.

Author: ZaydH

Diff for: pytorch_influence_functions/influence_function.py

@@ -67,9 +67,10 @@ def calc_loss(y, t):
     # if dim == [0, 1, 3] then dim=0; else dim=1
     ####################
     # y = torch.nn.functional.log_softmax(y, dim=0)
-    y = torch.nn.functional.log_softmax(y)
-    loss = torch.nn.functional.nll_loss(
-        y, t, weight=None, reduction='mean')
+    # y = torch.nn.functional.log_softmax(y)
+    # loss = torch.nn.functional.nll_loss(
+    #     y, t, weight=None, reduction='mean')
+    loss = torch.nn.functional.cross_entropy(y, t, weight=None, reduction="mean")
     return loss