Excel spreadsheet Great Circle calculator

I need to setup an Excel spreadsheet to calculate Great Circle distance and
bearing from a list of latitude and longitude data. In columns A,B,.....
what formulae do I need?

=3963*(ACOS(COS(A1)*COS(A2)*COS(B1-B2))+(SIN(A1)*SIN(A2))) doesn't work for
the distance


--
Mr. Lynndel Humphreys




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William Kahan gives a stable formula at this link:
http://www.cs.berkeley.edu/~wkahan/Math128/angle.pdf
Note that he doesn't include the radius of the planet, you have to multiply
his 'v' (in radians) by the radius of the earth.
He's giving the angle between two stars using alt-azimuth coordinates, but
his 'a' is the longitude difference, 'h' the latitude difference, and 'H'
the latitude of the first point in your application. You should filter out
the trivial cases where the tangents blow up, but the formula seems to work
anyway even if you don't (in Open Office 1.3).

Murray Anderson



"Lynndel Humphreys" wrote in message
...
I need to setup an Excel spreadsheet to calculate Great Circle distance
and
bearing from a list of latitude and longitude data. In columns A,B,.....
what formulae do I need?

=3963*(ACOS(COS(A1)*COS(A2)*COS(B1-B2))+(SIN(A1)*SIN(A2))) doesn't work
for
the distance


--
Mr. Lynndel Humphreys




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