in reply to Distance Between Geographical Coordinates
I believe I mentioned Math::Trig to you. It is in the standard perl distribution. From the pod:
The pod goes on with an example.GREAT CIRCLE DISTANCES You can compute spherical distances, called great circle distances, by importing the "great_circle_distance" function: use Math::Trig 'great_circle_distance' $distance = great_circle_distance($theta0, $phi0, $theta1, $phi1, [, $rho]); The great circle distance is the shortest distance between two points on a sphere. The distance is in "$rho" units. The "$rho" is optional, it defaults to 1 (the unit sphere), therefore the distance defaults to radi ans. If you think geographically the theta are longitudes: zero at the Green which meridian, eastward positive, westward negative--and the phi are lat itudes: zero at the North Pole, northward positive, southward negative. NOTE: this formula thinks in mathematics, not geographically: the phi zero is at the North Pole, not at the Equator on the west coast of Africa (Bay of Guinea). You need to subtract your geographical coordinates from pi/2 (also known as 90 degrees). $distance = great_circle_distance($lon0, pi/2 - $lat0, $lon1, pi/2 - $lat1, $rho);
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