MATLAB Programming/Alternatives to MATLAB
GNU Octave and LabVIEW MathScript are systems for numerical computations with an m-file script language that is mostly compatible with MATLAB. Both alternatives can replace MATLAB in many circumstances. While a good deal of the content of this book will also apply to both Octave and LabVIEW MathScript, it is not guaranteed to work in exactly the same manner. Differences and comparison between MATLAB and Octave are presented in Comparing Octave and MATLAB. Julia language was also made to replace MATLAB, with similar syntax/semantics, while having some deep differences (e.g. generics/multiple dispatch). See also Julia for MATLAB Users.
A short presentation of Octave and its history.