CODEWITHSUNDEEP
javascriptgpsdistance
Kannaiyan
Kannaiyan

Reputation: 13025

Distance formula for Longitude and Latitude from two directions

For any given latitude and longitude there should exist two distances. Once is clockwise direction and other is anti-clockwise direction. That is how sometimes flights fly too.

Below javascript worked fine in calculating the distance. I'm not sure whether it is clockwise or anti-clockwise. (referring South Down and North up)

What would be the formula to find both directions?

var R = 6371; // km
var dLat = (lat2-lat1).toRad();
var dLon = (lon2-lon1).toRad();
var lat1 = lat1.toRad();
var lat2 = lat2.toRad();

var a = Math.sin(dLat/2) * Math.sin(dLat/2) +
        Math.sin(dLon/2) * Math.sin(dLon/2) * Math.cos(lat1) * Math.cos(lat2); 
var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a)); 
var d = R * c;

Edit:

I want to calculate clockwise and anti-clockwise path between two points. Practically flights use clockwise and anti-clockwise paths to reach the same point. They don't just use the direct path for commercial and regulatory reasons.

I just want a formula to calculate clockwise and anti-clockwise path to the same point.

Distance wise, the shortest straight path and longest straight path.

Upvotes: 0

Views: 901

Answers (1)

ColinE
ColinE

Reputation: 70122

If you read the description of the website where you cut and paste that code, you will find that it is the haversine forumla and that it provides the shortest distance.

The equation does not give you a simple clockwise or anticlockwise path, it is the most direct 'journey' from point to point.

Upvotes: 1

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