ulam crate

ulam spiral lib for rust.

Example usage:

```rs let mut ulam_points = HashMap::new();

for x in -201..201 { if x % 10 == 0 { println!("{x}"); } for y in -201..201 { let c = Coord::new(x, y); let a = ulam::getulampoint(&c);

    ulam_points.insert(
        a.value,
        c
    );
}

}

let c = Coord::new(20000, 20000); let a = ulam::getulampoint(&c);

println!("{}", a.value); println!("{:?}", ulam_points[&55]);

ulam::ulamspiralimg::generate(1000, 1_000) .unwrap() .save("./result.png"); ```