Logistic Sigmoid

Problem

Compute the logistic sigmoid function: σ(z) = 1 / (1 + exp(-z)).

Handle large positive and negative z correctly (avoid overflow).

Hint

Branch on the sign of z to avoid exp() overflow.

case 1

in: [0]

expected: 0.5

case 2

in: [100]

expected: 1

case 3

in: [-100]

expected: 0

case 4

in: [2]

expected: 0.8807970779778823

case 5

in: [-2]

expected: 0.11920292202211755

Starter codePython

import math
def sigmoid(z):
    # Your code here
    pass

5 test cases · run your code against them in the editor