Function rgsl::fit::mul_est

pub fn mul_est(x: f64, c1: f64, cov11: f64) -> (Value, f64, f64)

This function uses the best-fit linear regression coefficient c1 and its covariance cov11 to compute the fitted function y and its standard deviation y_err for the model Y = c_1 X at the point x.

Returns (Value, y, y_err).