Center of mass (alpha = 1 / (1 + com)). Exclusive with span/halflife/alpha.
Span (alpha = 2 / (span + 1)). Default smoothing parameter. Exclusive with com/halflife/alpha.
Halflife (alpha = 1 - 0.5^(1/halflife)). Exclusive with com/span/alpha.
Smoothing parameter directly. Exclusive with com/span/halflife.
https://screamer.readthedocs.io/en/latest/ for the Python reference and full details.
x - EwBeta(x,y) * y - EW hedge-adjusted residual.