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Showing posts from January, 2018

Softmax function, softmax regression.

T he softmax function is also called the normalized exponential function.  It is a generalization of the  logistic function  that "squashes" a  K -dimensional vector  {\displaystyle \mathbf {z} }  of arbitrary real values to a  K -dimensional vector  {\displaystyle \sigma (\mathbf {z} )}  of real values in the range [0, 1] that add up to 1.  In  probability theory ,  t he output of the softmax function can be used to represent a  categorical distribution  – that is, a  probability distribution  over  K  different possible outcomes.  Example:  We know that every image in MNIST is of a handwritten digit between zero and nine. So there are only ten possible things that a given image can be. We want to be able to look at an image and give the probabilities for it being each digit. For example, our model might look at a picture of a nine and be 85% sure it's a nine, but give a 5% chan...