NAME

       GIS::Distance::Cosine - Spherical law of cosines distance calculations.

DESCRIPTION

       Although this formula is mathematically exact, it is unreliable for small distances.  See
       GIS::Distance::MathTrig for related details.

       A faster (XS) version of this formula is available as GIS::Distance::Fast::Cosine.

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

FORMULA

           a = sin(lat1) * sin(lat2)
           b = cos(lat1) * cos(lat2) * cos(lon2 - lon1)
           c = arccos(a + b)
           d = R * c

SEE ALSO

       •   <https://en.wikipedia.org/wiki/Spherical_law_of_cosines>

SUPPORT

       See "SUPPORT" in GIS::Distance.

AUTHORS

       See "AUTHORS" in GIS::Distance.

LICENSE

       See "LICENSE" in GIS::Distance.