A sigmoid function is a generic term refering to S-like functions that have a step-like nature, but are smooth without the discontinuity of the threshold function. This maes them more emnable to use in machine learning as, in general, continuity aids learning.
Used in Chap. 6: page 76; Chap. 7: page 99; Chap. 9: pages 126, 127; Chap. 10: page 139; Chap. 21: page 337
Also known as sigmoid
Sigmoid function smoothly limits extreme values