Sigmoid prime

sig-prime.py

import torch

#----------- Implementing the math -----------#

def sigmoid_prime(z):
  return sigmoid(z) * (1 - sigmoid(z))

z = torch.tensor([[2.], [-3.]], requires_grad=True)

sig_p = sigmoid_prime(z)

#----------- Using Pytorch autograd -----------#

torch_sig.backward(torch.tensor([[1.], [1.]]))

#----------- Comparing outputs -----------#

print(f"Pytorch Sigmoid': \n{z.grad} \nOur Sigmoid': \n{sig_p}")
'''
Out:
Pytorch Sigmoid': 
tensor([[0.1050],[0.0452]]) 
Our Sigmoid': 
tensor([[0.1050],[0.0452]])
'''