A statistical software package for Unix and Windows, created by MathSoft. S-Plus is a very useful and powerful
program for analyzing data, fitting models to the data, and plotting graphs of the data in many different ways to make it easy
to see which models fit best. If what you want to do with your data is too complicated to be done from the S-Plus command
line, you can use the S programming language which comes with S-Plus. S-Plus is not free software, but there exists a free
version called R.