Astro::Constants version 0.07
-----------------------------

This module provides a large number of physical constants which are
useful to Astronomers. The module itself is essentially a wrapper
around the astroconst package of Jeremy Balin, whose home page is
currently http://clavelina.as.arizona.edu/astroconst/

The module allows you to write code like

  use Astro::Constants::CGS qw(:long);
  print "The Schwarzschild radius of the sun is ",
        2 * GRAVITATIONAL * MASS_SOLAR / LIGHT_SPEED ** 2,
        " centimetres\n";

or

  use Astro::Constants::MKS qw(:short);
  print "The Schwarzschild radius of the sun is ",
        2 * $A_G * $A_msun / $A_c ** 2,
        " metres\n";

It also provides some subroutines to access the list of constants
available, a description of those constants, the precision associated
with a constant and print out numbers in a easier to read form.

Why not just use astroconst directly?
-------------------------------------

A good question. This module is not required to use the astroconst
package, but it does provide a more structured, "perlish", interface
to the data from the astroconst package.

Requirements
------------

Version 5.6.0 or later of perl.

Although not needed by this module, the L<PDL|PDL> package 
(http://pdl.perl.org/) is strongly suggested if you are interested 
in doing any serious numerical computation in perl.

The astroconst package is *not* required, since this module contains
all the necessary information from the 


Files
-----

README		- this file
astroconst.dat	- the original data file from Jeremy
build.PL	- during the make, it parses the 2 input files
		  and writes the CGS and MKS modules
convert.pl	- a little script for J and I to play with.  it
		  converts astroconst.dat to factory.dat 
		  (new format)
factory.dat	- new format for the data file including
		  short name, long name, description, CGS value
		  MKS value and precision

everything else is already listed in the MANIFEST file

Installation
------------

The module follows the standard perl module installation method,
namely:

	perl Makefile.pl
	make
	make test
	make install

If you want to add in your own constants or override the factory defaults,
run make, edit the site_const.dat file and then run make again.  If you have
a pre-existing site_const.dat file, drop it in place before running make.

The Future
----------

The file astroconst.dat is the officially sanctioned constants from 
Jeremy.  Site specific constants go in the site_const.dat file.  Edit
this file before you run make.  If you have an existing site_const.dat
file, it will NOT be overwritten.

We are hoping to move to an XML format for the constants.  This could lead
to a dependancy on XML::Parser for generating site-specific constants.

Slashdot commentary on the new XML Schema 1.1 spec is at
http://developers.slashdot.org/developers/03/01/23/228230.shtml?tid=95&tid=156

Author & Copyright
------------------

Boyd Duffee, perl@cs.keele.ac.uk

Copyright 2003, Boyd Duffee

astroconst.dat belongs to Jeremy Bailin

All rights reserved.  There is no warranty.
This program is free software; you can redistribute
it and/or modify it under the same terms as Perl itself.
(Debian users may assume the use of the Artistic Licence)
