1. The Cactus Team Albert Einstein Institute cactus@cactuscode.org
Introduction
The Cactus Team
Albert Einstein Institute

2. Cactus Plug-In “Thorns” (modules) Core “Flesh” remote steering
extensible APIs
ANSI C
Fortran/C/C++
parameters
driver
scheduling
equations of state
Core “Flesh”
input/output
error handling
black holes
interpolation
make system
boundary conditions
grid variables
SOR solver
coordinates
wave evolvers
multigrid

3. Cactus Architecture Cactus Thorns Computational Toolkit Toolkit
Flesh
Configure
Make
CST
Operating Systems
SuperUX
Irix
Linux
Unicos
HP-UX
Solaris
AIX
OSF NT

4. Thorn Architecture Thorn Parameter Files Configuration Files
and Testsuites
Configuration Files
????
Source Code
????
Fortran
Routines C
Routines
C++
Routines
Documentation!
Make
Information

5. Thorn Collections
CactusBase
CactusPUGH
CactusPUGHIO
CactusElliptic
+...
Cactus Computational Toolkit
For organizational convenience, thorns are grouped into arrangements
may have related functionality (e.g. IO or Maxwell solvers)
may have the same author
may contain everything needed for one problem
We call a collection of arrangements, a toolkit e.g.
Cactus Computational Toolkit
Cactus Relativity Toolkit

6. History
Cactus originated in 1997 as a code for numerical relativity, following a long line of codes developed at the NCSA and then the AEI.
Numerical Relativity: complicated 3D hyperbolic/elliptic PDEs, dozens of equations, thousands of terms, many people from very different disciplines working together, needing a fast, portable, flexible, easy-to-use, code which can incorporate new technologies without disrupting users.
Originally: Paul Walker, Joan Masso, John Shalf, Ed Seidel.
Cactus 4.0, August 1999: Total rewrite and redesign of code, learning from experiences with previous versions.

7. Community Code Designed from the outset to be freely available:
Released under the GNU GPL
Try to use freely available software options where possible:
More choice
Can use and develop anywhere
Welcome contributions:
Bug fixes, feature requests, comments
Modules/Thorns
Community
Mailing Lists
Shared modules
CVS versioning system

8. Who Is Using It? Numerical Relativity: Astrophysics: Aerospace:
Albert Einstein Institute, Washington University, Penn State University, UT at Texas, UC at Santa Barbara, U. Pittsburg, Southampton University, ...
Astrophysics:
NCSA (Zeus Code), EU Network (10 institutes)
Aerospace:
Pilot projects with DLR (German Aviation and Space Center)
Application for computer science based projects
Grid Application Development Sys (GrADS)
European Grid Forum (Egrid)
Astrophysics Collaboratory, KDI
Gigabit Computing, DFN
Looking for new applications ...

9. Who Is Developing It? Computer scientists at Albert Einstein Institute
Konrad-Zuse-Zentrum
NCSA
NERSC
NASA
Washington University
Rutgers
Argonne National Laboratory
University of Chicago
+ others

10. State of the Art
Production runs (using e.g. 512 processors of T3E, 256 processors of Origin 2000)
Remote visualization, viewing e.g. IsoSurfaces, flowlines, in real time on a local machine
Remote steering, changing parameters for e.g. output
Monitoring and interacting with remote runs from a web browser
Distributing computing, running a job on coupled remote machines with different architectures
Portals for e.g. job submission and management

11. Numerical Relativity Simulations
State of the Art
Numerical Relativity Simulations
Albert Einstein Institute
Washington University
Viz: Werner Benger

12. Support Web site: www.CactusCode.org Users Guide, Thorn Guide HOWTOs
Also available with Cactus distributions
Still being completed … please complain if something is missing!
HOWTOs
References for common questions, includes HOWTO-QuickStart
Tutorials
Help desk
Bug tracking
Mailing lists