pub fn diff_central(xs: &[f64], ys: &[f64]) -> Result<Vec<f64>, String>Expand description
Central difference approximation of the derivative.
Given paired arrays xs (abscissae) and ys (ordinates) of length n >= 3,
returns n-2 derivative estimates at the interior points xs[1..n-1]:
dy/dx[i] ≈ (ys[i+1] - ys[i-1]) / (xs[i+1] - xs[i-1])
This is a second-order accurate approximation.