Perl module to calculate geographic distances

 GIS::Distance calculates distances between geographic points on, at the
 moment, planet Earth. Various FORMULAS are available that provide different
 levels of accuracy versus speed.
 .
 GIS::Distance::Fast, a separate distribution, ships with C implementations of
 some of the formulas shipped with GIS::Distance. If you're looking for speed
 then install it and the ::Fast formulas will be automatically used by this
 module.