Run results for: Fast approx. atan2 vs Math.atan2 vs cached atan2 (v8 optimization buster + local scope)

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 16_2 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/16.2 Mobile/15E148 Safari/604.1

Browser: Mobile Safari 16

Operating system: iOS 16.2

Device Platform: Mobile

Date tested: one year ago

Test name	Executions per second
Math.atan2	903404.4 Ops/sec
fast approx. atan2	1415211.5 Ops/sec
cached Math.atan2	1137680.6 Ops/sec

Script Preparation code:

const abs = Math.abs, min = Math.min, max = Math.max, PI = Math.PI, PI2 = PI / 2;
var fastAtan2 = (y, x) => {
     let ax = abs(x);
     let ay = abs(y);
     let a = min(ax, ay) / max(x, y);
     let s = a * a;
     let r = ((-0.0464964749 * s + 0.15931422) * s - 0.327622764) * s * a + a;
     if (ay > ax) r = PI2 - r;
     if (x < 0) r = PI - r;
     if (y < 0) r = -r;
     return r;
}; //this is the fastest i can get it rn
var atan2 = Math.atan2;

Tests:

Math.atan2
eval(''); var k = [1, .23, 0.12, 929, 8172, 9.2, 21.2].map(e => Math.atan2(e, .5));
fast approx. atan2
eval(''); var k = [1, .23, 0.12, 929, 8172, 9.2, 21.2].map(e => fastAtan2(e, .5));
cached Math.atan2
eval(''); var k = [1, .23, 0.12, 929, 8172, 9.2, 21.2].map(e => atan2(e, .5));

Run results for: Fast approx. atan2 vs Math.atan2 vs cached atan2 (v8 optimization buster + local scope)

Math.atan2

fast approx. atan2

cached Math.atan2