最小二乗法 in Rust

lsm.rs

use std::io;

fn main() {
    let mut sxi  :f64 = 0.0;
    let mut syi  :f64 = 0.0;
    let mut sxiyi:f64 = 0.0;
    let mut sxi2 :f64 = 0.0;

    let mut n :f64 = 0.0;

    loop {
        let mut line = String::new();

        let size = io::stdin().read_line(&mut line)
            .ok()
            .expect("failed to read line");

        if size <= 1 {
            break;
        }

        let words :Vec<&str> = line.split_whitespace()
            .collect();

        if words.len() < 2 {
            println!("Please input two numbers.");
            continue;
        }

        let xi = words[0].parse::<f64>()
            .expect("value of X is invalid");
        let yi = words[1].parse::<f64>()
            .expect("value of Y is invalid");

        sxi += xi;
        syi += yi;
        sxiyi += xi*yi;
        sxi2 += xi*xi;
        n += 1.0;
    }

    if n > 1.0 {
        let a0 = (sxi2*syi - sxiyi*sxi) / (n*sxi2 - sxi*sxi);
        let a1 = (n*sxiyi - sxi*syi) / (n*sxi2 - sxi*sxi);

        println!("{}", a0);
        println!("{}", a1)
    }else{
        println!("Data is not enough.");
    }
}