pub fn rolling_std(values: &[f64], window: usize) -> Vec<f64>Expand description
Rolling sample standard deviation of the non-NULL values in a trailing window, by Welford’s algorithm.
Outputs NAN for the first window - 1 rows and wherever the window holds
fewer than two values — including window == 1, where a sample standard
deviation divides by zero. Returning 0.0 there, which this used to do,
asserts that a single reading has no spread; it has no measurable
spread, which is what NULL says.