Function shooting_method 

pub fn shooting_method(
    f: impl Fn(f64, &[f64]) -> Vec<f64>,
    t_span: (f64, f64),
    ya: f64,
    yb: f64,
    dt: f64,
    tol: f64,
    max_iter: usize,
) -> Vec<(f64, f64)>