Aran Clary Deltac >
GIS-Distance-0.08 >
GIS::Distance::Formula::MathTrig

Module Version: 0.08
GIS::Distance::Formula::MathTrig - Great cirlce distance calculations using Math::Trig.

This formula uses Math::Trig's great_circle_distance function which at this time uses math almost exactly the same as the GIS::Distance::Cosine formula. If you want to use the GIS::Distance::Cosine formula you may find that this module will calculate faster (untested assumption). For some reason this and the Cosine formula return slight differences at very close distances. This formula has the same drawbacks as the Cosine formula.

Normally this module is not used directly. Instead GIS::Distance is used which in turn interfaces with the various formula classes.

lat0 = 90 degrees - phi0 lat1 = 90 degrees - phi1 d = R * arccos(cos(lat0) * cos(lat1) * cos(lon1 - lon01) + sin(lat0) * sin(lat1))

As stated in the Math::Trig POD.

This method is called by GIS::Distance's distance() method.

Aran Clary Deltac <bluefeet@cpan.org>

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

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