Mathematical helper functions and types.
NEUQUANT Neural-Net quantization algorithm by Anthony Dekker, 1994. See "Kohonen neural networks for optimal colour quantization" in "Network: Computation in Neural Systems" Vol. 5 (1994) pp 351-367. for a discussion of the algorithm. See also http://www.acm.org/~dekker/NEUQUANT.HTML
Shared mathematical utility functions.