Math.hypot()

The Math.hypot() function returns the square root of the sum of squares of its arguments, that is:

Math.hypot(v1,v2,,vn)=i=1nvi2=v12+v22++vn2\mathtt{\operatorname{Math.hypot}(v_1, v_2, \dots, v_n)} = \sqrt{\sum_{i=1}^n v_i^2} = \sqrt{v_1^2 + v_2^2 + \dots + v_n^2}

Syntax

Math.hypot([value1[, value2[, ...]]])

Parameters

value1, value2, ...
Numbers.

Return value

The square root of the sum of squares of the given arguments. If at least one of the arguments cannot be converted to a number, NaN is returned.

Description

Calculating the hypotenuse of a right triangle, or the magnitude of a complex number, uses the formula Math.sqrt(v1*v1 + v2*v2), where v1 and v2 are the lengths of the triangle's legs, or the complex number's real and complex components.  The corresponding distance in 2 or more dimensions can be calculated by adding more squares under the square root: Math.sqrt(v1*v1 + v2*v2 + v3*v3 + v4*v4).  

This function makes this calculation easier and faster; you simply call Math.hypot(v1, v2) , or Math.hypot(v1, v2, v3, v4, ...).

Math.hypot also avoids overflow/underflow problems if the magnitude of your numbers is very large. The largest number you can represent in JS is Number.MAX_VALUE, which is around 10308. If your numbers are larger than about 10154, taking the square of them will result in Infinity. For example, Math.sqrt(1e200*1e200 + 1e200*1e200) = Infinity .  If you use hypot() instead, you get better answer: Math.hypot(1e200, 1e200) = 1.4142...e+200 . This is also true with very small numbers.  Math.sqrt(1e-200*1e-200 + 1e-200*1e-200) = 0, but Math.hypot(1e-200, 1e-200) =1.4142...e-200.

Because hypot() is a static method of Math, you always use it as Math.hypot(), rather than as a method of a Math object you created (Math is not a constructor).

If no arguments are given, the result is +0. If any of the arguments is ±Infinity, the result is Infinity. If any of the arguments is NaN (unless another argument is ±Infinity), the result is NaN. If at least one of the arguments cannot be converted to a number, the result is NaN.

With one argument, Math.hypot() is equivalent to Math.abs().

Polyfill

A naive approach that does not handle overflow/underflow issues:

if (!Math.hypot) Math.hypot = function() {
  var y = 0, i = arguments.length, containsInfinity = false;
  while (i--) {
    var arg = arguments[i];
    if (arg === Infinity || arg === -Infinity)
      containsInfinity = true
    y += arg * arg 
  }
  return containsInfinity ? Infinity : Math.sqrt(y)
}

A polyfill that avoids underflows and overflows:

if (!Math.hypot) Math.hypot = function () {
  var max = 0;
  var s = 0;
  var containsInfinity = false;
  for (var i = 0; i < arguments.length; ++i) {
    var arg = Math.abs(Number(arguments[i]));
    if (arg === Infinity)
      containsInfinity = true
    if (arg > max) {
      s *= (max / arg) * (max / arg);
      max = arg;
    }
    s += arg === 0 && max === 0 ? 0 : (arg / max) * (arg / max);
  }
  return containsInfinity ? Infinity : (max === 1 / 0 ? 1 / 0 : max * Math.sqrt(s));
};

Examples

Using Math.hypot()

Math.hypot(3, 4);          // 5
Math.hypot(3, 4, 5);       // 7.0710678118654755
Math.hypot();              // 0
Math.hypot(NaN);           // NaN
Math.hypot(NaN, Infinity); // Infinity
Math.hypot(3, 4, 'foo');   // NaN, since +'foo' => NaN
Math.hypot(3, 4, '5');     // 7.0710678118654755, +'5' => 5
Math.hypot(-3);            // 3, the same as Math.abs(-3)

Specifications

Specification
ECMAScript (ECMA-262)
The definition of 'Math.hypot' in that specification.

Browser compatibility

Update compatibility data on GitHub
DesktopMobileServer
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung InternetNode.js
hypotChrome Full support 38Edge Full support 12Firefox Full support 27IE No support NoOpera Full support 25Safari Full support 8WebView Android Full support 38Chrome Android Full support 38Firefox Android Full support 27Opera Android Full support 25Safari iOS Full support 8Samsung Internet Android Full support 3.0nodejs Full support 0.12

Legend

Full support  
Full support
No support  
No support

See also