NAME

       GIS::Distance::Haversine - Exact spherical distance calculations.

DESCRIPTION

       This is the default distance calculation for GIS::Distance as it keeps a good balance
       between speed and accuracy.

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

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

FORMULA

           dlon = lon2 - lon1
           dlat = lat2 - lat1
           a = (sin(dlat/2))^2 + cos(lat1) * cos(lat2) * (sin(dlon/2))^2
           c = 2 * atan2( sqrt(a), sqrt(1-a) )
           d = R * c

SEE ALSO

       •   <http://mathforum.org/library/drmath/view/51879.html>

       •   <http://www.faqs.org/faqs/geography/infosystems-faq/>

SUPPORT

       See "SUPPORT" in GIS::Distance.

AUTHORS

       See "AUTHORS" in GIS::Distance.

LICENSE

       See "LICENSE" in GIS::Distance.