GNU Octave is a high-level language, primarily intended for numerical computations. It provides a convenient command line interface for solving linear and nonlinear problems numerically, and for performing other numerical experiments using a language that is mostly compatible with Matlab.
C. Bird, D. Pattison, R. D'Souza, V. Filkov, and P. Devanbu. Proceedings of the 16th ACM SIGSOFT International Symposium on Foundations of software engineering, page 24--35. New York, NY, USA, ACM, (2008)