pi_monte_carlo.ark

[c] func printf(fmt: ^u8, ...);
[c] func srand(seed: uint);
[c] func time(ptr: u64) -> uint;
[c] func rand() -> int;
[c] func sqrt(in: f64) -> f64;

func randFloat() -> f64 {
    RAND_MAX := 2147483647; // hack for now

    return f64(C::rand()) / f64(RAND_MAX);
}

func calculate(iters: int) -> f64 {
    radius: f64 = 10.0;
    width := radius * 2.0;

    mut totalInCircle: u64 = 0;

    mut i := 0;
    for i < iters {
		dx := randFloat() * width - radius;
		dy := randFloat() * width - radius;

		if C::sqrt(dx*dx+dy*dy) < radius {
			totalInCircle += 1;
		}

        i += 1;
    }

    return 4.0 * f64(totalInCircle) / f64(iters);
}

pub func main() -> int {
    C::srand(C::time(0));

    iters := 20000000;
    res := calculate(iters);
    C::printf(c"Result of Monte Carlo pi estimation with %d iterations:\n", iters);
    C::printf(c"%f\n", res);
    return 0;
}