NAME

       GIS::Distance::MathTrig - Great cirlce distance calculations using Math::Trig.

DESCRIPTION

       This formula uses Math::Trig's "great_circle_distance()" which at this time uses math
       almost exactly the same formula as the GIS::Distance::Cosine formula.  And the Cosine
       formula is about 5% faster than this formula.

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

FORMULA

           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 documentation.

SUPPORT

       See "SUPPORT" in GIS::Distance.

AUTHORS

       See "AUTHORS" in GIS::Distance.

LICENSE

       See "LICENSE" in GIS::Distance.