This archive contains an Installer.app package for octave-1.1.1, a free matlab clone.
This was particularly painful to build because it required the following to build: gcc-2.6.3 (or higher), libg++-2.6.2 (or higher), f2c (fairly recent). Enjoy.
From the octave docs, Introduction:
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. It may also be used as a batch-oriented