Many mathematical packages are available from NETLIB
(http://www.netlib.org/)
and ACM TOMS
(http://www.acm.org/toms/)
.
ARPACK can be found at
http://www.caam.rice.edu/software/ARPACK/
.
Information
about the National Energy Research Supercomputing Center can be found on
the web at http://www.nersc.gov/
.