Distance between 2 points

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Modified: 2007/09/03 04:45 by ViaVE Visitor
Distance between 2 points

Returns the distance between two points (lat/long) in miles or kilometers.

Params:

point1 = new VELatLong(x, y);
point1 = new VELatLong(x2, y2);
miles = boolean (true returns distance in miles, false returns distance in kilometers)

Usage: 
map = new VEMap('myMap');
map.LoadMap();
getDistance(new VELatLong(0,0), new VELatLong(100, 100), true);


Refactored Code: 


// Calculate distance between two points specified by latitude/longitude using law of cosines.
// ref: http://www.movable-type.co.uk/scripts/LatLong.html
function getDistance(p1, p2, miles) {
	p1.Latitude= latLonToRadians(p1.Latitude);
	p1.Longitude= latLonToRadians(p1.Longitude);
	
	p2.Latitude= latLonToRadians(p2.Latitude);
	p2.Longitude= latLonToRadians(p2.Longitude);

	var R = 6371; // earth's mean radius in km
	var dLat  = p2.Latitude- p1.Latitude;
	var dLong = p2.Longitude- p1.Longitude;
	var a = Math.sin(dLat/2) * Math.sin(dLat/2) +
		Math.cos(p1.Latitude) * Math.cos(p2.Latitude) * Math.sin(dLong/2) * Math.sin(dLong/2);
	var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
	var disKm = R * c;
	var disMiles = disKm * 0.6214;

	return (miles ? disMiles : disKm);
}

//  convert lat/long in degrees to radians
function latLonToRadians( point ) {
	return point * Math.PI / 180;	
}



Orginal Code: 


// Calculate distance between two points specified by latitude/longitude using law of cosines.
// ref: http://www.movable-type.co.uk/scripts/LatLong.html
function getDistance( point1, point2, miles) {
	var p1 = getCoord(point1);
	p1.lat = latLonToRadians(p1.lat);
	p1.lon = latLonToRadians(p1.lon);
	
	var p2 = getCoord(point2);
	p2.lat = latLonToRadians(p2.lat);
	p2.lon = latLonToRadians(p2.lon);

	var R = 6371; // earth's mean radius in km
	var dLat  = p2.lat - p1.lat;
	var dLong = p2.lon - p1.lon;
	var a = Math.sin(dLat/2) * Math.sin(dLat/2) +
		Math.cos(p1.lat) * Math.cos(p2.lat) * Math.sin(dLong/2) * Math.sin(dLong/2);
	var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
	var disKm = R * c;
	var disMiles = disKm * 0.6214;

	return (miles ? disMiles : disKm);
}

// converts a VE point str to an object
function getCoord( point ) {
	var p = new Object();
	point = point.toString();
	p.lat = point.split(",")0;
	p.lon = point.split(",")1;
	
	return p;
}

//  convert lat/long in degrees to radians
function latLonToRadians( point ) {
	return point * Math.PI / 180;	
}



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