the loss is nan when i make the memory in NTM bigger?

[ghost]

In my task, when i make the memory size (50X50) with clipnorm = 10 the loss gives good numbers but if the memory is (50X512) with clipnorm = 10 or even 5 it gives nan why?

[EderSantana]

I haven't checked that problem. Perhaps the softmax is vanishing. Will check this later. Thanks for the report