LALMatrixTransform.c

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/*
*  Copyright (C) 2007 David Churches, Duncan Brown, Jolien Creighton
*
*  This program is free software; you can redistribute it and/or modify
*  it under the terms of the GNU General Public License as published by
*  the Free Software Foundation; either version 2 of the License, or
*  (at your option) any later version.
*
*  This program is distributed in the hope that it will be useful,
*  but WITHOUT ANY WARRANTY; without even the implied warranty of
*  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
*  GNU General Public License for more details.
*
*  You should have received a copy of the GNU General Public License
*  along with with program; see the file COPYING. If not, write to the
*  Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
*  MA  02111-1307  USA
*/

/*  <lalVerbatim file="LALMatrixTransformCV">
Author: Sathyaprakash, B. S.
$Id: LALMatrixTransform.c,v 1.10 2007/06/08 14:41:42 bema Exp $
</lalVerbatim>  */

/*  <lalLaTeX>

\subsection{Module \texttt{LALMatrixTransform.c}}
A routine to transform a second rank tensor under a given transformation.

\subsubsection*{Prototypes}
\vspace{0.1in}
\input{LALMatrixTransformCP}
\idx{LALMatrixTransform()}
\begin{itemize}
   \item \texttt{n,} Input, dimension of the matrix (currently, and possibly always, only 3)
   \item \texttt{data1,} Input, transformation matrix
   \item \texttt{data2,} Input, matrix whose transformation is required
   \item \texttt{data3,} Output, transformed matrix
\end{itemize}

\subsubsection*{Description}
Given the matrix of transformation in \texttt{data1} and a second rank tensor
\texttt{data2}, this routine computes the transformed tensor in \texttt{data3}.

\subsubsection*{Algorithm}
$$ C_{ij} = A_{im} A_{jl}  B_{ml}.$$

\subsubsection*{Uses}
None.

\subsubsection*{Notes}

\vfill{\footnotesize\input{LALMatrixTransformCV}}

</lalLaTeX>  */



#include <lal/LALInspiralBank.h>

NRCSID(LALMATRIXTRANSFORMC, "$Id: LALMatrixTransform.c,v 1.10 2007/06/08 14:41:42 bema Exp $");

/*  <lalVerbatim file="LALMatrixTransformCP"> */

void LALMatrixTransform (LALStatus *status, 
                         INT4 n, 
                         REAL8 **data1, 
                         REAL8 **data2, 
                         REAL8 **data3)
{ /* </lalVerbatim> */

   INT4 i, j, l, m;

   INITSTATUS(status, "LALMatrixTransform", LALMATRIXTRANSFORMC);
   ATTATCHSTATUSPTR(status);
   ASSERT (data1,  status, LALINSPIRALBANKH_ENULL, LALINSPIRALBANKH_MSGENULL);
   ASSERT (data2,  status, LALINSPIRALBANKH_ENULL, LALINSPIRALBANKH_MSGENULL);
   ASSERT (data3,  status, LALINSPIRALBANKH_ENULL, LALINSPIRALBANKH_MSGENULL);

   for (i=0; i<n; i++) {
   for (j=0; j<n; j++) {
      data3[i][j] = 0.0;
      for (l=0; l<n; l++) {
      for (m=0; m<n; m++) {
         data3[i][j] += data1[i][m]*data2[m][l]*data1[j][l];
      }}
   }}
   DETATCHSTATUSPTR(status);
   RETURN(status);
}

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