Neural Networks & Backpropagation
From logistic regression to a trained MLP, with every gradient derived
Build a neural network from the ground up: why stacked linear layers collapse and nonlinearity is the point, the neuron and layer with shapes and parameter counting, activation functions (sigmoid, tanh, ReLU, Leaky ReLU, GELU, SiLU) and their failure modes, loss and output-layer pairings with the log-sum-exp stability trick, computation graphs and reverse-mode autodiff, a full hand derivation of backprop for a 2-layer softmax-cross-entropy MLP, autograd mechanics, Xavier/He initialization, vanishing and exploding gradients, finite-difference gradient checking, and a fully numeric forward/backward/SGD worked example.
Practice questions (6)
-
View →
Derive the Gradient of Softmax Cross-Entropy
Intermediate -
View →
Count the Parameters of an MLP
Beginner · Free -
View →
Why Zero Initialization Fails, and What to Do Instead
Intermediate -
View →
Diagnose a Network Whose Hidden Activations Are All Zero
Intermediate -
View →
Why Reverse-Mode Autodiff Wins for Training
Advanced