PHP: Convert coordinates from degrees to decimal format

PHP: Convert coordinates from degrees to decimal format
by Janeth Kent Date: 11-04-2013

 

This code will convert longitude and latitude in D'M'S format into a decimal format. It also contains the function to do the reverse.

The example below does contain a couple of strange lines of code. You will notice that we seperate the integer and floating point values from the decimal format using a set of string functions, instead of using the math round or floor functions. This fixes a 'feature' in some versions of PHP that causes it to behave in an unpredictable manner when handling math with floating points.
For example, if you include the code print(91.1 - 91); in PHP you may not get the result you expect. You will actually get 0.099999999999994, not 1 ! This tends to throw of the calculations in the example.

function DMStoDEC($deg,$min,$sec)
{
// Converts DMS ( Degrees / minutes / seconds )
// to decimal format longitude / latitude

    return $deg+((($min*60)+($sec))/3600);
}   

function DECtoDMS($dec)
{
// Converts decimal longitude / latitude to DMS
// ( Degrees / minutes / seconds )

// This is the piece of code which may appear to
// be inefficient, but to avoid issues with floating
// point math we extract the integer part and the float
// part by using a string function.

    $vars = explode(".",$dec);
    $deg = $vars[0];
    $tempma = "0.".$vars[1];

    $tempma = $tempma * 3600;
    $min = floor($tempma / 60);
    $sec = $tempma - ($min*60);

    return array("deg"=>$deg,"min"=>$min,"sec"=>$sec);
}   
?>

 

 
by Janeth Kent Date: 11-04-2013 hits : 7516  
 
Janeth Kent

Janeth Kent

Licenciada en Bellas Artes y programadora por pasión. Cuando tengo un rato retoco fotos, edito vídeos y diseño cosas. El resto del tiempo escribo en MA-NO WEB DESIGN AND DEVELOPMENT.