which java package do you recommend for computing eigenvectors/eigenvalues? I know about JMathTools and JAMA; do you have some pro/cons for these packages? Other suggestions?
For a more centralized place on numerical computing in Java take a look at this website http://math.nist.gov/javanumerics/#libraries , that covers well known libraries presenting them in a convenient manner.
What has been suggested so far is covered on that site, plus many other packages.
Take the time and decide upon one that suits your needs. Enjoy.