pub fn acf(x: &[f64], nlags: usize) -> Array1<f64>Expand description
The biased autocorrelation function for lags 0..=nlags.
Uses the biased (divide-by-n) autocovariance estimator
gamma_k = (1/n) sum_{t=k}^{n-1} (x_t - xbar)(x_{t-k} - xbar), then
acf_k = gamma_k / gamma_0.