| Re: compare longitude and latitude values of two tables
Wilfried: That would give you what I was calling a "corrected Pythagoras". It is quick, but not hugely accurate. Might be good enough for this query though.
iirc, the nautical mile is defined for a specific latitude - the Earth is not a sphere, so the length of an arc second of latitude varies between the Equator and the Poles.
On top of that you have to correct for the geoid, but this will be a smaller (and more difficult!) correction.
Richard |