What is the Computational Toolkit?

Cactus is architectured to consist of modules (we call them thorns) which plug into a core code (we call it the flesh) which contains the APIs and infrastructure to glue the thorns together.

The flesh on it's own doesn't actually do anything. The thorns contain all the real activity, and can usually be divided into application thorns (typically written by scientists, solving problems in physics, astrophysics, engineering, etc) and infrastructure thorns (typically written by computational scientists, providing IO, interpolations, drivers, elliptic solvers etc). We group thorns together into arrangements, depending on their functionality and applicability.

The Cactus Computational Toolkit is a set of arrangements providing general computational infrastructure for many different applications. This page describes the different functionality provided by different thorns in the Computational Toolkit, for details of how to use the Toolkit, see the Documentation links.

Note that all the thorns in the Toolkit can be used for parallel, or single processor, applications.

Finding Out More

• See the documentation in each thorn, either on these web pages, or by typing gmake ThornGuide in your Cactus installation.
• Browse the configuration files for thorn configuration files
• We know that the documentation is patchy in many places, please let us know where it is lacking and we can give you the information you need and hopefully improve the docs.

Drivers

A driver thorn is the most important thorn to have ... you need one if you are using any grid variables in Cactus, since it is responsible for all the memory management and, if you're working on a parallel machine, for communications.

Unigrid Parallel Driver

CactusPUGH/PUGH

Boundary Conditions

In general, the boundary conditions listed can be applied in 1, 2 or 3-dimensional spacetimes to any of the supported datatypes and can be individually applied in any direction.

Periodic boundary conditions

CactusPUGH/PUGH

Symmetry boundary conditions

CactusBase/CartGrid3D

Scalar boundary conditions

CactusBase/Boundary

Radiation boundary conditions

CactusBase/Boundary

Flat boundary conditions

CactusBase/Boundary

Robin boundary conditions

CactusBase/Boundary

Copy boundary conditions

CactusBase/Boundary

Coordinate Systems

So far we only have a general thorn for 3D Cartesian coordinates, mainly because we're trying to think of a clever way to include many different coordinate systems with a simple choice of parameters.

Cartesian coordinates

CactusBase/CartGrid3D

Time coordinate

CactusBase/Time

Adaptive Courant timestep

CactusBase/Time

Output Methods

Output methods and data formats are also described on our Visualization page. In general output methods can be used in 1, 2 or 3-dimensions, and are extremely customizable through parameter choices.

Hyperslabbing (for finding data to output)

CactusPUGH/PUGHSlab

ASCII output

CactusBase/IOASCII

ASCII output of scalars (e.g. max, min)

CactusBase/IOBasic

Constant value isosurfaces

CactusPUGHIO/IsoSurfacer

HDF5 binary format

CactusPUGHIO/IOHDF5

FlexIO binary format

CactusPUGHIO/IOFlexIO

Jpegs

CactusIO/IOJpeg

Checkpointing

CactusPUGHIO/IOHDF5, CactusPUGHIO/IOFlexIO

Interpolators and Reduction Operators

The interpolators and reduction operators described can be applied in 1, 2 or 3-directions, on all supported data types.

First, second or third order interpolation

CactusPUGH/PUGHInterp

Maximum and Minimum

CactusPUGH/PUGHReduce

Sum

CactusPUGH/PUGHReduce

Norms

CactusPUGH/PUGHReduce

Elliptic Solvers

SOR

CactusElliptic/EllSOR

Iterative (PETSc)

CactusElliptic/EllPETSc

Utilities

Simulation web server

CactusConnect/HTTPD, CactusConnect/HTTPDExtra

Tool for locating NaNs, infinities, and uninitialised memory

CactusUtils/NaNChecker