GNU Octave is a high-level language, primarily intended for numerical computations. It provides a convenient command-line interface (CLI) for solving linear and nonlinear problems numerically, and for performing other numerical experiments using a language that is mostly compatible with MATLAB.
Mathematica is a mathematics software program used to help with science, math, and engineering fields. It can be used for industrial work, or for educational purposes. It allows integration of computation to many different types of fields and work flows.
GNUPlot is a command-line program that can generate two- and three-dimensional plots of functions, data, and data fits.