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Re: What returns from distance function?
Posted by: Mike McCutcheon
Date: May 11, 2010 06:21PM

I have tested the distance() function on:
1. points on the same line of longitude
2. points on the same line of latitude
and compared the results with the Google Earth ("GE") measuring tool.

distance() and GE *seem* to:
- agree when the points are on the same line of longitude but
- disagree when the points are on the same line of latitude (or any other line).

For example, if 2 points are one degree of longitude apart on the same line of latitude, the distance() function wrongly says that the distance is 60 nautical miles (whatever the latitude). Obviously this isn't true as lines of longitude converge at the poles.

I really hope I'm wrong, in which case I apologize; I find it hard to believe that distance() wouldn't allow for the latitude and bearing of the line between the points.

But if distance() *is* wrong:
- what do we have to do to get it corrected ?
- meanwhile, what formula must we use to process the result of distance() to allow for the latitude and bearing of the line between 2 points ?

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