SciLab is an incredibly useful software used to perform complex mathematical calculations, plots, etc. It works using  matrices. As explained in their introductory document:

“Scilab is not a computer algebra system. It calculates only with numbers. All calculations are done with matrices, although this may go unnoticed. Even if the concept of matrices is unknown, vectors and sequences of numbers can explain it, as they are, in fact, matrices of dimension 1 × n or n × 1 and a number is itself a matrix of dimension 1 × 1”


Take a look at a quick introductory video, made by myself (IN SPANISH):