arn-language/src/math.js

A functional golfing language

module.exports.listPrimes = function primeSieve(n) {
    var a = Array(n = Math.ceil(n / 2)),
        t = (Math.sqrt(4 + 8 * n) - 2) / 4,
        u = 0,
        r = [];
    
    for (let i = 1; i <= t; i++) {
        u = (n - i) / (1 + 2 * i);
        for (let j = i; j <= u; j++) a[i + j + 2 * i * j] = true;
    }

    for (let i = 0; i <= n; i++) !a[i] && r.push((i * 2 + 1).toString());

    // Remove the last element if it's greater than the inputted number
    if (r[r.length - 1] > n * 2) r.pop();
    return r;
}

module.exports.factorize = function getFactors(num) {
    let fac = [], 
        i = 1, 
        ind = 0;
    
    while (i <= Math.floor(Math.sqrt(num))) {
        if (num % i === 0) {
            fac.splice(ind, 0, i);
            if (i != num / i) fac.splice(-ind, 0, num / i);
            ind++;
        }
        i++;
    }
    
    let temp = fac[fac.length - 1];
    fac[fac.length - 1] = fac[0];
    fac[0] = temp;
    
    return fac;
}