GLASS - The free-form gravitational lens modeling framework
-----------------------------------------------------------

GLASS is a software package for modeling strong gravitianal lenses. It produces
an ensemble of possible models that fit the observed input data and conform to
certain constraints specified by the user. This document describes the installation
process and how to run a typical case.

Dependecies
-----------

GLASS is currently written in Python 2.7 with a small portion written in C. GLASS
does not support Python 3 at the current time. GLASS makes heavy use of the numerical
routines provided by the numpy and scipy packages as well as the linear programming
package GLPK. This latter package, and its Python interface, is provided with GLASS
and will be installed automatically in the GLASS build directory by following the
directions below.


Downloading and unpacking GLASS
-------------------------------

GLASS can be downloaded as a .zip file or using git from GitHub:

https://github.com/jpcoles/glass

After obtaining the source code, it will, by default, be located in a directory
called 'glass'.

Building GLASS
--------------

GLASS and the GLPK can be built simply by running the command 'make' in the 
glass source code directory. This will unpack the GLPK packages and compile
them. It will also build and install GLASS. All compiled code and executables
will exist under the glass/build directory.

Running GLASS
-------------

In the glass directory there is a script called 'run_glass' which will execute
GLASS with the proper environment paths regardless of the current directory.

For example, running 'run_glass' with no arguments produces the following output:

    $ ./run_glass
    Usage: glass.py <input>


The Examples directory contains a number of example input files. The simplest example
is B1115.gls

Run this example from the Examples directory:

    Examples $ ../run_glass B1115.gls

This will produce an output file B1115.state which contains the entire running state
of the modeling including all of the generated models.


Analyzing the Output
--------------------

In the 'Tools' directory there is a proram called 'viewstate.py' uses GLASS as a
library and can generate plots from the output state file. To see the default
plots run the command

    Examples $ ../run_glass ../Tools/viewstate.py B1115.state