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Latitude and longitude

, 30 Aug 2012
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Introduction

The simple code allows you to measure the distance between two places on earth with latitude and longitude pairs in meters.

Background 

Finding proximity between two points is important. In day to day life we speak about distances in Meters and KM. But mathematically how to convert the distance between two {latitude,longitude} pairs?

Using the code 

The logic is simple. Convert the values to radians. Than calculate d=sine(latitude distance)^2+cosine(longitude distance). distance=2* tan2(sqrt(d),sqrt(1-d)). Multiply the distance with earth radius to get geographical distance in radians. All you have to do is get it converted to meters.  

public class DistanceInMeter
{
	
public static double distFrom(double lat1, double lng1, double lat2, double lng2) {
    double earthRadius = 3958.75;
    double dLat = toRadians(lat2-lat1);
    double dLng = toRadians(lng2-lng1);
    double a = Math.Sin(dLat/2) * Math.Sin(dLat/2) +
               Math.Cos(Math.toRadians(lat1)) * Math.Cos(Math.toRadians(lat2)) *
               Math.Sin(dLng/2) * Math.Sin(dLng/2);
    double c = 2 * Math.Atan2(Math.sqrt(a), Math.sqrt(1-a));
    double dist = earthRadius * c;

    int meterConversion = 1609;

    return (dist * meterConversion);
    }

	static double  toRadians(double degree)
	{
		return (degree*0.0174532925 );
	}
}  

Points of Interest

You can import Google map in you application and find all places within some distance. This function is typically helpful for spatial data mining. 

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

About the Author

Grasshopper.iics
CEO Integrated Ideas
India India
gasshopper.iics is a group of like minded programmers and learners in codeproject. The basic objective is to keep in touch and be notified while a member contributes an article, to check out with technology and share what we know. We are the "students" of codeproject.
 
This group is managed by Rupam Das, an active author here. Other Notable members include Ranjan who extends his helping hands to invaluable number of authors in their articles and writes some great articles himself.
 
Rupam Das is mentor of Grasshopper Network,founder and CEO of Integrated Ideas Consultancy Services, a research consultancy firm in India. He has been part of projects in several technologies including Matlab, C#, Android, OpenCV, Drupal, Omnet++, legacy C, vb, gcc, NS-2, Arduino, Raspberry-PI. Off late he has made peace with the fact that he loves C# more than anything else but is still struck in legacy style of coding.
Rupam loves algorithm and prefers Image processing, Artificial Intelligence and Bio-medical Engineering over other technologies.
 
He is frustrated with his poor writing and "grammer" skills but happy that coding polishes these frustrations.
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Comments and Discussions

 
GeneralYou should state your assumptions PinmemberJohn Brett31-Aug-12 0:47 
GeneralRe: You should state your assumptions PingroupGrasshopper.iics31-Aug-12 15:01 

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