struct SPH {
    x: Vec<f32>,
    y: Vec<f32>,
    h: Vec<f32>,
}

impl SPH {
    fn new() -> Self {
        SPH {
            x: vec![0.; 10],
            y: vec![0.; 10],
            h: vec![0.; 10],
        }
    }
}

// pair(d_x, d_y, d_h, s_x, s_y, s_h);
fn pair(d_x: &[f32], d_y: &[f32], d_h: &mut [f32], s_x: &[f32], s_y: &[f32], s_h: &[f32]) {
    for i in 0..d_h.len() {
    for j in 0..s_h.len(){

        d_h[i] += s_x[j] * s_y[j] * d_x[i] * d_y[i];
    }
    }
}
macro_rules! macro_pair{
    ($func_name:ident, $dest:ty, $source:ty) => {
        $func_name(& dest.x, &dest.y, &mut dest.h, &source.x, &source.y, &source.h);
    }
}

fn main() {
    let mut sph_d = SPH::new();
    let sph_s = SPH::new();
    // pair(&sph_d.x, &sph_d.y, &mut sph_d.h, &sph_s.x, &sph_s.y, &sph_s.h);
    macro_pair!(pair, sph_d, sph_s);
}