If GSL Shell exists is thanks to the many high quality free software projects on which it is based.
The GSL library is an highly valuable library with a well designed API, good C coding and a complete and accurate documentation. It is the merit of the GSL library if many numerical algorithms are easily available for non-specialist FORTRAN programmers.
The AGG library is another outstanding free software library that does leverage the C++ template systems to achieve graphical results of excellent quality with very good execution performances.
Last, but not least, the LuaJIT2 made a really big difference with its outstanding JIT code generator. Thanks to LuaJIT2 it is possible to easily write code in Lua and achieve performances close to optimized C code.
Luckily some people have kindly contributed some valuable implementations for GSL Shell, so many thanks to Lesley and Benjamin for their previous help.
Finally I would like to thanks the Lua and LuaJIT mailing list, Mike Pall and the Lua authors for their advices and helps.
Many thanks also to my wife, Gosia, for her patience and her support.