This complements an earlier question on usable, fast C++ matrix libraries.
I've looked at the Java Matrix Benchmark, and it seems like the performance of java matrix libraries is all over the place. The Apache Commons Math library seems like a simple solution, but I'm curious for others recommendations.
Specifically, I'm curious which libraries are much easier/more performant than the others, and/or if Java library writers are better off just using JNI to call to an existing, better developed native matrix libraries. (Though that seems like it could make the code less portable or more of a hassle to setup.)