One neuron: a weighted sum, then an activation function

output g(w₁x₁ + w₂x₂ + b) over the input plane

Backpropagation by hand: 2 inputs, 3 sigmoid hidden units, 1 sigmoid output, L = ½(o − t)², t = 0.85

Train a small network in your browser (full-batch gradient descent, cross-entropy)

decision regions and training points

training loss