fn main() {
    let funcs = [
        ("+", sum as fn(f64, f64) -> f64),
        ("-", sub),
        ("*", mult),
        ("/", div),
        ("^", pow)
    ];

    for &(name, func) in funcs.iter() {
        for a in 1..4 {
            for b in 1..4 {
                println!("{} {} {} = {}", a, name, b, func(a as f64, b as f64));
            }
        }
        println!("");
    }
}

fn sum(a : f64, b : f64) -> f64 {
    a + b
}

fn sub(a : f64, b : f64) -> f64 {
    a - b
}

fn pow(a : f64, b : f64) -> f64 {
    a.powf(b)
}

fn mult(a : f64, b : f64) -> f64 {
    a * b
}

fn div(a : f64, b : f64) -> f64 {
    a / b
}