GNU Octave - GNU Octave is a programming language for scientific computing.
QtOctave - QtOctave: a front-end for Octave/un Front-End para Octave
MATLAB - A high-level language and interactive environment for numerical computation, visualization, and programming
Xcos - Xcos is a graphical editor to design hybrid dynamical systems models.
WIRIS cas - WIRIS cas is a web-based program for mathematical calculations.
Function Analyzer - see the graph of a function