Run results for: trigata

Run details:

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 10_3_3 like Mac OS X) AppleWebKit/603.1.30 (KHTML, like Gecko) CriOS/66.0.3359.122 Mobile/14G60 Safari/602.1

Browser: Chrome Mobile iOS 66

Operating system: iOS 10.3.3

Device Platform: iPhone

Date tested: 6 years ago

Test name	Executions per second
native	220312.9 Ops/sec
alt	190447.8 Ops/sec
alt2	193421.0 Ops/sec
alt3	194542.1 Ops/sec
alt4	159030.5 Ops/sec
alt5	163623.7 Ops/sec

Script Preparation code:

function rand(min, max) {
    return Math.floor(Math.random() * (max - min + 1)) + min;
}

function angle(x, y) {
  let result = Math.atan(y / x);
  if (x < 0) {
    result += Math.PI;
  } else if (y < 0) {
    result += 2 * Math.PI;
  }
  return result;
}

function angle2(x, y) {
    if (x == 0)
      return (y == 0) ? 0 : (y > 0 ? Math.PI/2 : -Math.PI/2)
  
    var atan_xy = Math.atan(y / x)
    if (x > 0)
      return atan_xy
    else // x < 0
      return atan_xy + (y < 0 ? -Math.PI : Math.PI)
}

function myAtan2(a, b)
{
    var atan2val;
    if (b > 0) {
        atan2val = Math.atan(a/b);
    }
    else if ((b < 0) && (a >= 0)) {
        atan2val = Math.atan(a/b) + Math.PI;
    }
    else if ((b < 0) && (a < 0)) {
        atan2val = Math.atan(a/b) - Math.PI;
    }
    else if ((b = 0) && (a > 0)) {
        atan2val = Math.PI / 2;
    }
    else if ((b = 0) && (a < 0)) {
        atan2val = 0 - (Math.PI / 2 );
    }
    else if ((b = 0) && (a = 0)) {
        atan2val = 1000;
    }
  
    return atan2val;
}

function matan2(y, x){
  const c1 = Math.PI / 4;
  const c2 = Math.PI * 3 / 4;

  if (y == 0 && x == 0){
    return 0;
  }

  const abs_y = Math.abs(y);
  let angle;
  if (x >= 0){
    angle = c1 - c1 * ((x - abs_y) / (x + abs_y));
  } else {
    angle = c2 - c1 * ((x + abs_y) / (abs_y - x));
  }

  if (y < 0){
    return -angle;
  }

  return angle;
}

function atandd(y, x) {
    const ONEQTR_PI = Math.PI / 4.0;
	const THRQTR_PI = 3.0 * Math.PI / 4.0;
	let r, angle;
	let abs_y = Math.abs(y) + 0.0000000001;
	
	if ( x < 0 ) {
		r = (x + abs_y) / (abs_y - x);
		angle = THRQTR_PI;
	} else {
		r = (x - abs_y) / (x + abs_y);
		angle = ONEQTR_PI;
	}

	angle += (0.1963 * r * r - 0.9817) * r;
	
	if ( y < 0 )
		return( -angle );
	else
		return( angle );
}

Tests:

native
var xO = rand(1, 1000); var yO = rand(1, 1000); Math.atan(yO, xO);
alt
var xT = rand(1, 1000); var yT = rand(1, 1000); angle(xT, yT);
alt2
var xD = rand(1, 1000); var yD = rand(1, 1000); angle2(xD, yD);
alt3
var xC = rand(1, 1000); var yC = rand(1, 1000); myAtan2(xC, yC);
alt4
var xZ = rand(1, 1000); var yZ = rand(1, 1000); matan2(xZ, yZ);
alt5
var xU = rand(1, 1000); var yU = rand(1, 1000); atandd(yU, xU)

native

alt

alt2

alt3

alt4

alt5