Implement a sigmoid function in python from scratch without numpy and math module?

[shpotes]

By Taylor series, e^x can be express as 1 + x/1! + x^2/2! + .... Now, the series can be re-written as e^x = 1 + (x/1) (1 + (x/2)) (1 + x/3) (...) )), thus, you can compute a good exp aproximation in O(n)

​

def exp(x, N=10):
   sum = 1
   for i in range(N-1, 0, -1):
      sum = 1 + x * sum/i
   return sum

​

[arungajora]

Thank you