Octave is a program for numerical computations similar to Matlab, which aims to solve numerical problems of various kinds: algebra linear calculation of roots of nonlinear equations, integration of functions, polynomials, matrices, integration of ordinary differential equations, differential algebraic equations, etc.
Octave provides an interpreted programming language whose syntax is similar to Matlab, and is also compatible with that application. Language can be extended with functions and procedures through dynamic modules.
For simple problems a command line is available, while for more complex problems you can create scripts that include several commands.
From the functions entered, you can generate a graphical representation of the same, either two-dimensional or three-dimensional. This is done using the plot (2D) and plot3 (3D) commands.
There is a graphical environment called QtOctave, in case you want a more comfortable interface than the command line that Octave offers.
In the official site you can find documentation in Spanish, with manuals and examples to learn how to use this tool, while you can also consult this extensive manual in PDF .
Octave 4.2.0 is the latest version, updated in November 2016, of this software for numeric calculation that can be downloaded for free. It works with Windows, Linux and Mac OS X. For the case of Mac the instructions must be followed to install it through a packaging manager such as Fink.
Download Octave (Windows)
Download Octave (Other operating systems)