February 2018
Beginner to intermediate
258 pages
5h 47m
English
We start off with probably the most basic classifier, the logistic regression, to be specific multinomial logistic regression as it is a multiclass case. It is a probabilistic linear classifier parameterized by a weight matrix W (also called coefficient matrix) and a bias (also called intercept) vector b. And it maps an input vector x to a set of probabilities P(y=1), P(y=2),. . ., P(y-K) for K possible classes.
A multinomial logistic regression for two possible classes can be represented graphically as follows:

Suppose x is n-dimension, then the weight matrix W is of size n by K with each column Wk representing ...
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