Dear Lloyd,

I've picked this up rather late. If you still require the answer[s] then get
back to me including telling me whether you have a book of tables known as
"Norries Tables". If not I can give you an arithmetic method by calculator.
Basically you work out the D'Lat [difference in minutes of latitude] and
Dep(arture), then converting Dep into D'Long [differnce in minutes of
Longitude]. From which can be determined Dist(ance) and Co(arse) made good,
or of course the reverse having only course and distance find the rest.

Chris Spreckley



"Lloyd Sumpter" wrote in message
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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