Matlab, with all its strengths, is a traditional, imperative computation engine that, while useful for algorithm exploration, is not very useful for real-time or embedded system implementation. In view of this, the signal processing industry has largely migrated to a different paradigm for modeling systems, one based on block-diagram visualization coupled with hardware and software synthesis.
The Ptolemy SDF domain is a representative of a genre of such signal processing software environments. Notable commercial representatives include SPW, from the Alta Group at Cadence Design Systems, and Cossap from Synopsys. Why don't we use the commercial versions? Frankly, we find them harder to use and the software harder to maintain.