Colt is a package for scalable scientific and technical computing in Java. It
consists of several free Java libraries, for user convenience bundled under one
single uniform umbrella. Namely the Colt library, the Jet library, the CoreJava
library, and the Concurrent library.

The Colt library provides fundamental general-purpose data structures optimized
for numerical data, such as resizable arrays, dense and sparse matrices
(multi-dimensional arrays), linear algebra, associative containers and buffer
management.

WWW: http://acs.lbl.gov/~hoschek/colt/