From: firstname.lastname@example.org (Mark Brader) Organization: SoftQuad Inc., Toronto, Canada Date: 13 Oct 95 01:30:28 References: 1 2
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Karl Swartz (kls@ohare.Chicago.COM) writes: > acos( sin(lat1) * sin(lat2) + cos(lat1) * cos(lat2) * cos(theta) ) [Where acos is done in radians] > Multiply that by the radius of the earth (i.e., 6371.2 kilometers) to > get a reasonable approximation of the great circle distance. Right, it's a reasonable approximation. So don't be fooled by that "6371.2 km" -- that implies a spurious degree of precision. The radius of the Earth varies by more then 40 km between poles and equator. And if you want the distance flown rather than the ground distance covered, you also need to take the flying altitude into account! -- Mark Brader, email@example.com "I'm not a lawyer, but I'm pedantic and SoftQuad Inc., Toronto that's just as good." -- D Gary Grady My text in this article is in the public domain.