class documentation
class ExponentialMovingAverage(object):
Constructor: ExponentialMovingAverage(decay, dim, flg_init_with_data)
Exponential Moving Average, Variance, and SNR (Signal-to-Noise Ratio)
See http://www-uxsup.csx.cam.ac.uk/~fanf2/hermes/doc/antiforgery/stats.pdf