opnsense-ports/math/libneural/pkg-descr

libneural is an extremely tiny library for creating a software
three layer backpropagation neural network. This is useful for
a very wide variety of pattern recognition and classification
problems. It is written in C++, based on the standard algorithm
with NO fancy features like bias terms or momentum.

WWW: http://ieee.uow.edu.au/~daniel/software/libneural/