Determine the center point of multiple geographical locations in JS

center_geo.js

var Map = function(){}

/**
 * Calculate the Lat/Lng centerpoint of several Google Maps markers
 * Based on: https://gist.github.com/amites/3718961
 * @param  {array} latlngpoints
 * @return {Object}
 */
Map.prototype.calculateCenterPoint = function(latlngpoints){
	var x = 0,
		y = 0,
		z = 0,
		len = latlngpoints.length;

	for(var i = 0; i < latlngpoints.length; i++){
		var lat = latlngpoints[i].lat,
			lng = latlngpoints[i].lng;

		x += Math.cos(lat) * Math.cos(lng);
		y += Math.cos(lat) * Math.sin(lng);
		z += Math.sin(lat);
	}

	x = (x / len);
	y = (y / len);
	z = (z / len);

	var output = {
		lat: toDegrees(Math.atan2(z, Math.sqrt(x * x + y * y))), 
		lng: toDegrees(Math.atan2(y, x))
	};

	return output;
};

/**
 * Convert a radian value to degrees
 * @param  {float} fromRadian
 * @return {float)
 */
function toDegrees(fromRadian){
	return fromRadian / (Math.PI / 180); 
}

/**
 * Convery a degree value to a radian
 * @param  {float} fromDegree
 * @return {float}
 */
function toRadians(fromDegree){
	return fromDegree * (Math.PI / 180);
}