NAME
Geo::Compass::Variation - Accurately calculate magnetic declination and
inclination
SYNOPSIS
use Geo::Compass::Variation qw(mag_dec mag_inc);
my $lat = 53.1234567;
my $lon = -114.1234567;
my $alt = 1098;
my $declination = mag_dec($lat, $lon, $alt);
my $inclination = mag_inc($lat, $lon, $alt);
DESCRIPTION
This module calculates and returns the Magnetic declination and
inclination (dip) calculations based on WMM earth magnetism model for a
specified latitude and longitude pair.
See NOAA <
https://www.ngdc.noaa.gov/geomag/WMM/DoDWMM.shtml> for
details.
The WMM data is currently valid from January 1, 2015 through December
31, 2019. This module will be updated with new WMM data as it becomes
available.
EXPORT_OK
All functions must be imported explicitly:
use Geo::Compass::Variation qw(mag_dec mag_inc);
# or
use Geo::Compass::Variation qw(:all);
Note: The mag_dec function has an alias of mag_var which can be
imported explicitly, or with the :all tag.
FUNCTIONS
mag_dec
Calculates and returns the magnetic declination of a pair of GPS
coordinates.
Parameters:
$lat
Mandatory, Float: Latitude, in signed notation (eg: 53.1111111.
Negative is South and positive is North of the Equator.
$lon
Mandatory, Float: Longitude, in signed notiation (eg: -114.11111.
Negative is West and positive is East of the Prime Meridian.
$alt
Optional, Integer: Altitude above sea level, in metres. Defaults to 0.
$year
Optional, Integer|Float: The year to base the calculation from.
Defaults to YYYY.M, where YYYY is the year from localtime() and M is
the month number from localtime().
We will die() if the year is out of range of the current WMM
specification.
Return: A floating point number representing the magnetic declination.
mag_var
Simply an alias for "mag_dec".
mag_inc
Calculates and returns the magnetic inclination of a pair of GPS
coordinates.
Parameters:
Parameters are exactly the same as for the "mag_dec" function. Please
review that documentation section for full details.
Return: A floating point number representing the magnetic inclination.
mag_field
Core function that calcluates the raw magnetic field north component
($X), the east component ($Y) and the vertical component ($Z).
Takes the same parameters as "mag_dec". Please see that function's
documentation for full details.
AUTHOR
Steve Bertrand, <steveb at cpan.org>
ACKNOWLEDGEMENTS
All the thanks goes out to no_slogan
<
http://perlmonks.org/?node_id=78006> of Perlmonks for all of the core
functionality.
It was presented here <
http://perlmonks.org/?node_id=1191907>, in
response to this thread <
http://perlmonks.org/?node_id=1191753> I had
started regarding a code review of some prototype code I wrote to
calculate the direction between two pairs of GPS coordinates.
LICENSE AND COPYRIGHT
Copyright 2017 Steve Bertrand.
This program is free software; you can redistribute it and/or modify it
under the terms of either: the GNU General Public License as published
by the Free Software Foundation; or the Artistic License.
See
http://dev.perl.org/licenses/ for more information.
