Function rgsl::interpolation::eval_deriv2

pub fn eval_deriv2(
    interp: &Interp, 
    xa: &[f64], 
    ya: &[f64], 
    x: f64, 
    acc: &mut InterpAccel
) -> f64

This function returns the second derivative d2 of an interpolated function for a given point x, using the interpolation object interp, data arrays xa and ya and the accelerator acc.