get distance from many locations with google maps api v3

getdistance.php

/*
$locations = array('longitude,latitude')
*/
function getDistance($locations)
{
        $waypoints = $locations;
	if(count($waypoints) > 2)
	{
		unset($waypoints[0]);			
		unset($waypoints[count($locations) - 1]);			
	}else{
		$waypoints = array();
	}
	if($waypoints)
	{
		$waypoints = implode('|', $waypoints)
	}

	$parameterurl = array( 
			'origin'		=> $locations[0], 
			'destination'	        => $locations[count($locations) - 1],
			'waypoints'		=> $waypoints,
			'sensor'		=> 'false',
			'units'			=> 'driving'		
	); 

	$params_string = '';
	foreach($parameterurl as $var => $val){
		$params_string .= '&' . $var . '=' . urlencode($val);  
	}
		
	$url = 'https://maps.googleapis.com/maps/api/directions/json?'.ltrim($params_string, '&');
			
	$response = file_get_contents($url);
	$response = json_decode($response);
	$data = $response->routes[0]->legs;
	if($data)
	{
		$output = 0;
		foreach($data AS $location)
		{
			$output += $location->distance->value;
		}		
	}
	return $output;
}