S. Mandayam/ ANN/ECE Dept./Rowan University Artificial Neural Networks ECE /ECE Fall 2006 Shreekanth Mandayam ECE Department Rowan University Lecture 4 October 9, 2006
S. Mandayam/ ANN/ECE Dept./Rowan UniversityPlan Recall: Multilayer Perceptron Architecture Signal Flow Learning rule - Backpropagation Lab Project 2
S. Mandayam/ ANN/ECE Dept./Rowan University Multilayer Perceptron (MLP): Architecture x1x1 x2x2 x3x3 y1y1 y2y2 w ji w kj w lk Input Layer Hidden Layers Output Layer Inputs Outputs
S. Mandayam/ ANN/ECE Dept./Rowan University MLP: Characteristics Neurons possess sigmoidal (logistic) activation functions Contains one or more “hidden layers” Trained using the “backpropagation” algorithm MLP with 1-hidden layer is a “universal approximator” (t) t
S. Mandayam/ ANN/ECE Dept./Rowan University MLP: Signal Flow Function signal Error signal Computations at each node, j Neuron output, y j Gradient vector, dE/dw ji Forward propagation Backward propagation
S. Mandayam/ ANN/ECE Dept./Rowan University MLP Training Forward Pass Fix w ji (n) Compute y j (n) Backward Pass Calculate j (n) Update weights w ji (n+1) i j k Left Right i j k Left Right x y
S. Mandayam/ ANN/ECE Dept./Rowan University Lab Project 2 /fall06/ann/lab2.htmlhttp://engineering.rowan.edu/~shreek /fall06/ann/lab2.html
S. Mandayam/ ANN/ECE Dept./Rowan UniversitySummary