Factorials that will work with cuda?

autograd
1

Is there a way to do factorials that will work with cuda? I can use scipy.special.factorial if using the CPU, but it gives an error when using cuda (because it’s using numpy under the hood).

2

Hi ccook!

Yes. The Euler gamma function is essentially the factorial function.
Because it grows so fast we often use the logarithm of the gamma
function for numerical work. Pytorch provides torch.lgamma(), a
full-featured, cuda-enabled, autograd-enabled pytorch tensor function.

Best.

K. Frank

3

Wow, excellent – this worked perfectly. Thank you.

(One note for future readers is that it’s torch.lgamma(k+1).exp() ~= factorial(k) – the +1 is needed).

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