An Artificial Neuron

Weighted sums and activation

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• A neuron computes a weighted sum plus bias: $z = \sum w_i x_i + b$.
• An activation function (sigmoid, ReLU) bends the result.
• Sigmoid: $\sigma(z) = 1/(1 + e^{-z})$, with $\sigma(0) = 0.5$.

Steps

1. A cartoon of a brain cell
2. Weighted sum
3. Through the sigmoid
4. A soft switch
5. Why not stay linear?
6. ReLU