소프트맥스함수,softmax_function

Softmax (activation) function maps a vector of $K$ real values
into a probability distribution of $K$ possible outcomes,
i.e., a vector of $K$ real values that sum to 1.

Often used in the output layer.

즉 결과 벡터의 원소들의 합이 1이 되게.

$o_i = \frac{e^{z_i}}{\sum\nolimits_{i=1}^K e^{z_i}}$
(Kwak, Slide 2, p37)






AKA softargmax function