© 2000 Todd Neller.  A.I.M.A. text figures © 1995 Prentice Hall.  Used by permission.
Back-Propagation (cont.)
•Error computation makes use of the slope of the activation function, so we need to use continuous activation functions.
•The sigmoid function is typical.
sigmoid(x) = 1/(1 + e-x)
sigmoid'(x) = sigmoid(x)(1 – sigmoid(x))
• Error term Di = Erri*g'(ini)