Lens modelling code
The IGLOO modelling code control screen
The IGLOO lens modelling code
The "industry standard" lens modelling code is lensmodel, written by C. Keeton, which can be downloaded from his website. This code does pretty much everything you need, and has a lot of mass models and ways of optimizing models to agree with observational data.
The IGLOO (Interactive Gravitational Lens Optimization Olgorithm) code, developed at Manchester, is rather different in philosophy. It sacrifices richness of features (and sophistication of algorithm) to user-friendliness and small size of code. It is useful for a "first look" to see what is going on in a particular lens system, although it can be used for end-to-end modelling in any particular system using isothermal mass models, isothermal potentials, point sources or cusped mass distributions. It has a graphical interface based on PGPLOT so you will need to install this first. It also uses the Gnu Software Library which is distributed under the GPL. For cusped mass models it uses the codes cuspFS.f and spleFS.f written by K.-H. Chae, although the distributed version contains stubs for these two Fortran codes. The tar file contains rudimentary documentation, but help is obtainable interactively from the program itself. If you have comments or problems, please email to neal dt jackson at manchester dt ac dt uk (dt is a full stop and at is the @ sign) although I do not guarantee to fix things on any particular timescale.