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Calculates distance between two points using latitude and longitude in decimal degrees - IGOR Pro
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| // calculates spherical distance between two points on earth given coords in decimal degrees | |
| // uses haversine formula | |
| // radius of earth is taken to be 6371 km (IUGG/WGS-84 mean) | |
| Function SphericalDistanceBetweenTwoPoints(lat1, long1, lat2, long2) | |
| Variable lat1, long1, lat2, long2 | |
| // convert inputs in degrees to radians | |
| lat1*= pi/180 | |
| long1*= pi/180 | |
| lat2*= pi/180 | |
| long2*= pi/180 | |
| Variable dlon = long1 - long2 | |
| Variable dlat = lat1 - lat2 | |
| Variable aa = ((sin(dlat / 2) ^ 2) + cos(lat1) * cos(lat2) * (sin(dlon / 2) ^ 2)) | |
| Variable cc = 2 * atan2(sqrt(aa), sqrt(1 - aa)) | |
| Variable dd = 6371 * cc | |
| // return distance in metres | |
| return dd * 1000 | |
| end | |
| // example usage with two 1D waves called lat and lon, distance between rows 0 and 1 | |
| Print DistanceBetweenTwoPoints(lon[0],lat[0],lon[1],lat[1]) |
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Updated by cpr https://www.wavemetrics.com/comment/20517#comment-20517