# Computing

Our interest in parallel computing is motivated by
our investigations of QCD using the
transverse lattice method.
It is also used in
the Parallel Computing (CSC491) class.
Development of parallel lanczos methods for finding
the lowest eigenvalues of sparse matrices.
This research was conducted by Geneva undergraduate
students George McDaniel and Loren Silbaugh during the summer of 2000.
plan3.tgz is the resulting
package of Lanczos routines
for finding eigenvalues (and eigenvectors) of symmetric-real and
complex-hermitian sparse matrices. It has both a single-processor
and a parallel version. It is based on the
PLANSO
package by Wu and Simon.

## Semi-definite eigenvalue problem

In light-front quantization, one often has fields
that are constrained, not true dynamical degrees of freedom.
If one keeps constrained states in the system, the
resulting eigenvalue problem has the form
**A **`x` = `lambda` **E **`x`

where **A** and **E** are Hermitian and
**E** is positive semi-definite.
Currently, we assume **E** is also diagonal.
During the summer of 2004, Geneva student Justin Lambright
developed numerical methods for solving these problems.
See Justin Lambright's project summary (PDF)
(LaTeX).

As detailed in the project summary, we developed a
dense version semidefinite.f,
and a sparse version sparsesd.tgz which
uses
SPOOLES and
plan3.tgz.
A second sparse version
blocksparse.tgz
assumes the constrained part of the matrix is
block-diagonal; it does not use SPOOLES.
We have not yet parallelized this code.

See libaries by Yousaf Saad in Duluth

During June 2003, we set up an
8-node beowulf cluster using 16 AMD Opteron processors and
32 GBytes of memory.
As of August 2004, the operating system is a modification of
Fedora 2 for x86-64.
It is configured so that
one node acts as file server for the other seven nodes, which
are diskless.
The computers are connected via two parallel Gigabit
Ethernet networks.
During the summer of 2004,
extensive benchmarking of the system was performed by
Geneva student Jeremy Pace.
Here is his
summary of activities (PDF)
(LaTeX).

## Other Linux Stuff

- Setting up proxy ARP for just some interfaces is slightly tricky.
Including
`echo 1 > /proc/sys/net/ipv4/conf/eth?/proxy_arp`

in `rc.local`

won't work for network restarts.
Instead, here is a script that will be run automatically on startup:
`/sbin/ifup-local`

.
- Set the region on your DVD drive dvd_set.c.
- disk_backup is a shell script for performing
incremental backups. Normally it is run daily as a
`cron`

job.