JavaScript fmod

Returns the remainder of dividing x by y as a float

function fmod (x, y) {
    // Returns the remainder of dividing x by y as a float  
    // 
    // version: 909.322
    // discuss at: http://phpjs.org/functions/fmod    // +   original by: Onno Marsman
    // +      input by: Brett Zamir (http://brett-zamir.me)
    // +   bugfixed by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // *     example 1: fmod(5.7, 1.3);
    // *     returns 1: 0.5    
    var tmp, tmp2, p = 0, pY = 0, l = 0.0, l2 = 0.0;
    
    tmp = x.toExponential().match(/^.\.?(.*)e(.+)$/);
    p = parseInt(tmp[2], 10)-(tmp[1]+'').length;    tmp = y.toExponential().match(/^.\.?(.*)e(.+)$/);
    pY = parseInt(tmp[2], 10)-(tmp[1]+'').length;
    
    if (pY > p) {
        p = pY;    }
    
    tmp2 = (x%y);
    
    if (p < -100 || p > 20) {        // toFixed will give an out of bound error so we fix it like this:
        l  = Math.round(Math.log(tmp2)/Math.log(10));
        l2 = Math.pow(10, l);
        
        return (tmp2 / l2).toFixed(l-p)*l2;    } else {
        return parseFloat(tmp2.toFixed(-p));
    }
}

external links: original PHP docs | raw js source

Examples

Running

1	fmod(5.7, 1.3);

Should return

0.5

Dependencies

No dependencies, you can use this function standalone.

Open syntax issues

php.js uses JsLint to help us keep our code consistent and prevent some common bugs.

Eventually we want all code to pass or at least take into consideration most fixes suggested by JsLint, following this JsLint configuration we’ve decided on.

Authors

Thanks to the following developers, you get to have fmod goodness in JavaScript.

Onno Marsman ( original )
Brett Zamir ( input )
Kevin van Zonneveld ( bugfixed )

Comments

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Use:

[CODE]
your_stuff('here');
[/CODE]

for proper code formatting
By submitting code here you are allowing us to use it in php.js hence dual licensing it under the MIT and GPL licenses

Kevin van Zonneveld
6 Oct '08

@ Onno Marsman: Sharp, thanks again Onno.

Onno Marsman
5 Oct '08

The following comments should be removed, they are not true:

// % note: Examples in PHP & JS return: 0.8, but according
// % note: the PHP-manual's it should be 0.5. PHP manual seems to be incorrect?

Kevin van Zonneveld
1 Oct '08

@ Enrique GonzÃ¡lez: Whoops, my bad.

Enrique GonzÃ¡lez
1 Oct '08

The example 1 at rad2deg is wrong. It should be something like:

rad2deg (3.141592653589793)
returns 180

Kevin van Zonneveld
1 Oct '08

@ Enrique GonzÃ¡lez: Thank you so much!

Enrique GonzÃ¡lez
1 Oct '08

Two simple functions that translate deg to rad and viceversa:

function deg2rad(angle)
  {
  //*        example 1 : deg2rad (180)
  //*        returns 1 : 3.141592653589793
  return (angle/180)*Math.PI;  }
  
function rad2deg(angle)
  {
  //*        example 1 : deg2rad (pi())     //*        returns 1 : 3.141592653589793
  return (angle/Math.PI)*180;
  }

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