Data Science & ML
Intermediate

Sigmoid Function

Maps any real number to the range (0, 1); used in logistic regression.

Formula

σ(x)=11+e−x\sigma(x) = \frac{1}{1 + e^{-x}}

Variables

xInput value
eEuler number

Example

\sigma(0) = 0.5

Did You Know?

The sigmoid was the classic neural-network activation before ReLU took over.

activationlogistic