It's an academic topic called "Spherical Geometry"
There is a plane which cuts the two coordinate pairs and the Earth
center. A 'triangle' is drawn from the center and the two given
points. The included angle is found from which the great circle
distance is derived.

Brian Whatcott

On Thu, 04 Dec 2003 14:57:11 -0800, "Lloyd Sumpter"
wrote:


That will do it - thanks! Curious about how those formulae were developed,
though...

Lloyd


On Thu, 04 Dec 2003 14:46:15 +0000, SpamJam wrote:

You want http://williams.best.vwh.net/avform.htm

"Lloyd Sumpter" wrote in message
news
Hi,

I'm writing a program for Linux that displays position (from GPS) on a
scanned-in chart, and would like it to calculate distance from current
position to the cursor.

How do you calculate distance between two points using lat/long? If
they're due North/South, I can do it ( 1 minute of lat = 1 NM) but how do
you calculate distance from longitude? Perhaps some formula based on the
circumfrence of the Earth at the equator and the latitude?

Lloyd Sumpter

Huh? The earth isn't flat? When did that happen? (tic)

Dumb Ass! It's round. Kinda like a dinner plate. Be careful when you get
close to the edge.

When Joshua Slocum was sailing around the world and meet a head of state in
some island nation, that was the excepted explanation.

Steve
s/v Good Intentions

Dumb Ass! It's round. Kinda like a dinner plate. Be careful when you get
close to the edge.

When Joshua Slocum was sailing around the world and meet a head of state in
some island nation, that was the excepted explanation.

Steve
s/v Good Intentions

Huh? The earth isn't flat? When did that happen? (tic)