NAME
Geo::Ellipsoids - Standard perl Geo package for ellipsoids a, b, f and 1/f values.
SYNOPSIS
use Geo::Ellipsoids;
my $obj = Geo::Ellipsoids->new();
$obj->set('WGS84'); #default
print "a=", $obj->a, "\n";
print "b=", $obj->b, "\n";
print "f=", $obj->f, "\n";
print "i=", $obj->i, "\n";
print "e=", $obj->e, "\n";
print "n=", $obj->n(45), "\n";DESCRIPTION
CONSTRUCTOR
new
The new() constructor may be called with any parameter that is appropriate to the set method.
my $obj = Geo::Ellipsoid->new();
METHODS
set
Method sets the current ellipsoid. This method is called when the object is constructed (default is WGS84).
$obj->set(); #default WGS84
$obj->set('Clarke 1866'); #All built in ellipsoids are stored in meters
$obj->set({a=>1, b=>1}); #Custom Sphere 1 unit radiuslist
Method returns a list of known elipsoid names.
my @list=$obj->list;
my $list=$obj->list;
while (@$list) {
print "$_\n";
}a
Method returns the value of the semi-major axis.
my $a=$obj->a;b
Method returns the value of the semi-minor axis.
my $b=$obj->b;f
Method returns the value of flatting
my $f=$obj->f;i
Method returns the value of the inverse flatting
my $i=$obj->i;invf
Method synonym for the i method
my $i=$obj->infv;e
Method returns the value of eccentricity
my $e=$obj->e;e2
Method returns the value of eccentricity squared (e.g. e^2)
my $e=sqrt($obj->e2);n
Method returns the value of n given latitude (degrees). #What is n called?
my $n=$obj->n($lat);n_rad
Method returns the value of n given latitude (radians). #What is n called?
my $n=$obj->n_rad($lat);polar_circumference
Method returns the value of the semi-minor axis times 2*PI.
my $polar_circumference=$obj->polar_circumference;equatorial_circumference
Method returns the value of the semi-major axis times 2*PI.
my $equatorial_circumference=$obj->equatorial_circumference;shortname
Method returns the shortname, which is the hash key, of the current ellipsoid
my $shortname=$obj->shortname;longname
Method returns the long name of the current ellipsoid
my $longname=$obj->longname;data
Method returns a hash reference for the ellipsoid definition data structure.
my $datastructure=$obj->data;name2ref
Method returns a hash reference (e.g. {a=>6378137,i=>298.257223563}) when passed a valid ellipsoid name (e.g. 'WGS84').
my $ref=$obj->name2ref('WGS84')TODO
What should we do about bad input? I tend to die in the module which for most situations is fine. I guess you could always overload die to handle exceptions for web based solutions and the like.
Support for ellipsoid aliases in the data structure
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
Geo::Forward Geo::Ellipsoid Geo::Coordinates::UTM Geo::GPS::Data::Ellipsoid GIS::Distance