pub fn beta(real0: &[f64], real1: &[f64], period: usize) -> Vec<Option<f64>>Expand description
Rolling BETA of real0 against real1 (TA-Lib BETA). Uses period
trailing simple returns; beta = (n·Σxy − Σx·Σy) / (n·Σxx − (Σx)²) where
x are real0 returns and y are real1 returns. First value at index
period.