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\documentclass{article}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% MANPAGE like description setting for options, use as
% \begin{Lentry} \item[text] text \end{Lentry}
\usepackage{ifthen,calc}
\newcommand{\entrylabel}[1]{\mbox{\textsf{#1}}\hfil}
\newenvironment{entry}
{\begin{list}{}
{\renewcommand{\makelabel}{\entrylabel}
\setlength{\labelwidth}{90pt}
\setlength{\leftmargin}{\labelwidth+\labelsep}
}
}
{\end{list}}
\newlength{\Mylen}
\newcommand{\Lentrylabel}[1]{%
\settowidth{\Mylen}{\textsf{#1}}%
\ifthenelse{\lengthtest{\Mylen > \labelwidth}}%
{\parbox[b]{\labelwidth} % term > labelwidth
{\makebox[0pt][l]{\textsf{#1}}\\}} %
{\textsf{#1}} %
\hfil\relax}
\newenvironment{Lentry}
{\renewcommand{\entrylabel}{\Lentrylabel}
\begin{entry}}
{\end{entry}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{document}
\title{PUGHReduce}
\author{Gabrielle Allen, Thomas Radke}
\date{2000}
\maketitle
%
\abstract{Reductions operations which are performed using the PUGH driver}
%
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\section{Purpose}
%
This thorn registers a number of reduction operators with the flesh. The
reductions are performed using internals of the PUGH driver, so that this
thorn can only be used when {\tt CactusPUGH/PUGH} is active.\\
The reduction operations this thorn registers are\\
\begin{tabular}{|l|l|l|}
\hline
Reduction Operator & Calculates & By \\
\hline
{\tt minimum} & the minimum of a grid variable & $ \min{ GV } $ \\
{\tt maximum} & the maximum of a grid variable & $ \max{ GV } $ \\
{\tt sum} & the sum of the elements of a grid variable & $ \sum{ GV } $ \\
{\tt norm1} & the L1 norm of a grid variable & $ \left(\Sigma | GV | \right)/n $ \\
{\tt norm2} & the L2 norm of a grid variable & $ \sqrt{\Sigma GV^2}/n $ \\
{\tt norm\_inf} & the Inf norm of a grid variable & $ \max{| GV |} $ \\
\hline
\end{tabular}\\
In the formulas $GV$ is the grid variable to be reduced, and $n$ denotes the
number of its elements.
%
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\section{Examples}
%
The following C example illustrates how the get the maximum value of a grid
function.
%
\begin{verbatim}
int vindex; /* grid variable index */
CCTK_REAL result; /* resulting reduction value */
int target_proc; /* processor to hold the result */
int reduction_handle; /* handle for reduction operator */
char *reduction_name; /* reduction operator to use */
/* want to get the maximum for the wavetoy grid function */
reduction_name = "maximum";
vindex = CCTK_VarIndex ("wavetoy::phi");
/* the reduction result will be obtained by processor 0 only */
target_proc = 0;
/* get the handle for the given reduction operator */
reduction_handle = CCTK_ReductionHandle (reduction_name);
if (reduction_handle >= 0)
{
/* now do the reduction using the flesh's generic reduction API
(passing in one input, expecting one output value of REAL type) */
if (CCTK_Reduce (cctkGH, target_proc, reduction_handle,
1, CCTK_VARIABLE_REAL, &result, 1, vindex) == 0)
{
if (CCTK_MyProc (cctkGH) == target_proc)
{
printf ("%s reduction value is %f\n", reduction_name, result);
}
}
else
{
CCTK_VWarn (1, __LINE__, __FILE__, CCTK_THORNSTRING,
"%s reduction failed", reduction_name);
}
}
else
{
CCTK_VWarn (1, __LINE__, __FILE__, CCTK_THORNSTRING,
"Invalid reduction operator '%s'", reduction_name);
}
\end{verbatim}
%
%
% Automatically created from the ccl files by using gmake thorndoc
\include{interface}
\include{param}
\include{schedule}
\end{document}
|
