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

Run details:

User agent: Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Mobile Safari/537.36

Browser: Chrome Mobile 120

Operating system: Android

Device Platform: Mobile

Date tested: 2 years ago

Benchmark engine: Benchmark.js

fast approx. atan2

256K/s

cached Math.atan2

230K/s

Math.atan2

163K/s

View exact numbers

Test name	Executions per second
✓ fast approx. atan2	255,750 Ops/sec
cached Math.atan2	230,400 Ops/sec
Math.atan2	162,728 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));