NAME

Geo::Inverse - Calculate geographic distance from a lat & lon pair.

SYNOPSIS

  use Geo::Inverse;
  my $obj = Geo::Inverse->new(); # default "WGS84"
  my ($lat1,$lon1,$lat2,$lon2)=(38.87, -77.05, 38.95, -77.23);
  my ($faz, $baz, $dist)=$obj->inverse($lat1,$lon1,$lat2,$lon2); #array context
  my $dist=$obj->inverse($lat1,$lon1,$lat2,$lon2);              #scalar context
  print "Input Lat: $lat1  Lon: $lon1\n";
  print "Input Lat: $lat2 Lon: $lon2\n";
  print "Output Distance: $dist\n";
  print "Output Forward Azimuth: $faz\n";
  print "Output Back Azimuth: $baz\n";

DESCRIPTION

This module is a pure Perl port of the NGS program in the public domain "inverse" by Robert (Sid) Safford and Stephen J. Frakes.

CONSTRUCTOR

new

The new() constructor may be called with any parameter that is appropriate to the ellipsoid method which establishes the ellipsoid.

  my $obj = Geo::Inverse->new(); # default "WGS84"

METHODS

ellipsoid

Method to set or retrieve the current ellipsoid object. The ellipsoid is a Geo::Ellipsoids object.

  my $ellipsoid=$obj->ellipsoid;  #Default is WGS84

  $obj->ellipsoid('Clarke 1866'); #Built in ellipsoids from Geo::Ellipsoids
  $obj->ellipsoid({a=>1});        #Custom Sphere 1 unit radius

inverse

This method is the user frontend to the mathematics. This interface will not change in future versions.

  my ($faz, $baz, $dist)=$obj->inverse($lat1,$lon1,$lat2,$lon2);

TODO

Add more tests.

BUGS

Please send to the geo-perl email list.

LIMITS

No guarantees that Perl handles all of the double precision calculations in the same manner as Fortran.

AUTHOR

Michael R. Davis qw/perl michaelrdavis com/

LICENSE

Copyright (c) 2006 Michael R. Davis (mrdvt92)

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

SEE ALSO

Net::GPSD Geo::Ellipsoid GIS::Distance::GeoEllipsoid