Run results for: Fast Sqrt0

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/134.0.0.0 Safari/537.36 OPR/119.0.0.0

Browser: Opera 119

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
✓ Math.sqrt	6,056 Ops/sec
Quakes fast inverse sqrt.	41 Ops/sec

Script Preparation code:

var i;
var r;
var v = 2 ** 16;

function test1() {
    for (i = 0; i < 100000; ++i) {
        r = Math.sqrt(v);
    }
}

function test2() {
    for (i = 0; i < 100000; ++i) {
        r = Q_rsqrt(v) * v;
    }
}

//Based on the fast inverse square root function
// https://en.wikipedia.org/wiki/Fast_inverse_square_root
// Some original comments preserved for humor value
// Designed to try to mimic the original as closely as possible
function Q_rsqrt(number) {
    var i;
    var x2, y;
    const threehalfs = 1.5;

    x2 = number * 0.5;
    y = number;
    //evil floating bit level hacking
    var buf = new ArrayBuffer(4);
    (new Float32Array(buf))[0] = number;
    i = (new Uint32Array(buf))[0];
    i = (0x5f3759df - (i >> 1)); //What the fuck?
    (new Uint32Array(buf))[0] = i;
    y = (new Float32Array(buf))[0];
    y = y * (threehalfs - (x2 * y * y)); // 1st iteration
    //  y  = y * ( threehalfs - ( x2 * y * y ) );   // 2nd iteration, this can be removed

    return y;
}

Run results for: Fast Sqrt0

Compare Quakes fast inverse squareroot

Math.sqrt

Quakes fast inverse sqrt.