Geo::Forward - Calculate geographic location from lat, lon, distance, and heading.

  use Geo::Forward;
  my $obj = Geo::Forward->new(); # default "WGS84"
  my ($lat1,$lon1,$faz,$dist)=(38.871022, -77.055874, 62.888507083, 4565.6854);
  my ($lat2,$lon2,$baz) = $obj->forward($lat1,$lon1,$faz,$dist);
  print "Input Lat: $lat1  Lon: $lon1\n";
  print "Input Forward Azimuth: $faz\n";
  print "Input Distance: $dist\n";
  print "Output Lat: $lat2 Lon: $lon2\n";
  print "Output Back Azimuth: $baz\n";

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

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

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

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

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

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

Add tests for more ellipsoids.

Please send to the geo-perl email list.

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

Michael R. Davis qw/perl michaelrdavis com/

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.

Net::GPSD Geo::Spline Geo::Ellipsoid Geo::Ellipsoids