A simple function to validate latitude and longitude in php.

validateGeoCoords.php

<?php

function validateGeoCoords($lat=null,$lng=null) {
    return (trim($lat,'0') == (float)$lat) && (trim($lng,'0') == (float)$lng);
}

This may be a shorter validation as here (http://altafphp.blogspot.de/2013/11/validate-latitude-and-longitude-with.html) but not a good one as you do not proof the possible range of latitude (+- 90) and longitude (+-180)

its not the correct in http://altafphp.blogspot.de/2013/11/validate-latitude-and-longitude-with.html
but check the comment under it, that might be correct.... :)

To implement validation for latitude and longitude values we can write a logic that, latitude must be a number between -90 and 90 and the longitude between -180 and 180 degree inclusive. Yo can get the free source code from here