[rywang]

While we're on the subject, I'm curious if you've played with matrix-toolkits-java / netlib-java. I'm considering switching to it. I've had good experiences with the Lawson-Hanson non-negative least squares that comes with netlib.

[bedatadriven]

The netlib-java project is very convenient because it allows you to use optimized native netlib libs, and transparently fall back to the f2j (jvm bytecode) library when native libs are available.

The java version of netlib produced by f2j is unfortunately the unoptimized "reference implementation", so it's not terribly performant for large matrices.