Path: utzoo!utgpu!water!watmath!clyde!att!pacbell!ames!ll-xn!olsen
From: olsen@XN.LL.MIT.EDU (Jim Olsen)
Newsgroups: comp.mail.uucp
Subject: Re: lattitute/longitude problem
Keywords: latitude longitude C
Message-ID: <1055@xn.LL.MIT.EDU>
Date: 21 Jul 88 13:36:01 GMT
References: <256@telly.UUCP>
Reply-To: olsen@xn.UUCP (Jim Olsen)
Organization: MIT Lincoln Laboratory, Lexington, MA
Lines: 5

Here is a C expression which calculates the great-circle distance from
point (lat1,lon1) to point (lat2,lon2).  All quantities are in radians.
To convert the distance to kilometers, multiply by 6367.

     distance = acos(cos(lat2-lat1) * cos((lon2-lon1)*cos(lat1)));