NAME

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

SYNOPSIS

my $calc = GIS::Distance::MathTrig->new();
my $distance = $calc->distance( $lon1, $lat1 => $lon2, $lat2 );

DESCRIPTION

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

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 POD.

AUTHOR

Aran Clary Deltac <bluefeet@cpan.org>

LICENSE

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