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ordmmdmex.c
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Sun, Jul 13, 09:44

ordmmdmex.c
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/*
perm = ordmmdmex(X)
Computes multiple-minimum-degree permutation, for sparse
Cholesky. X is a sparse symmetric matrix; only its off-
diagonal sparsity structure is used.
Invokes SPARSPAK-A Release III.
% This file is part of SeDuMi 1.1 by Imre Polik and Oleksandr Romanko
% Copyright (C) 2005 McMaster University, Hamilton, CANADA (since 1.1)
%
% Copyright (C) 2001 Jos F. Sturm (up to 1.05R5)
% Dept. Econometrics & O.R., Tilburg University, the Netherlands.
% Supported by the Netherlands Organization for Scientific Research (NWO).
%
% Affiliation SeDuMi 1.03 and 1.04Beta (2000):
% Dept. Quantitative Economics, Maastricht University, the Netherlands.
%
% Affiliations up to SeDuMi 1.02 (AUG1998):
% CRL, McMaster University, Canada.
% Supported by the Netherlands Organization for Scientific Research (NWO).
%
% 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 this program; if not, write to the Free Software
% Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
% 02110-1301, USA
*/
#include "mex.h"
#define PERM_OUT plhs[0]
#define X_IN prhs[0]
/* ============================================================
SUBROUTINES:
============================================================ */
/* ------------------------------------------------------------
GETADJ - Copies off-diagonal entries from C-style sparse
matrix (cjc,cir) to Fortran style sparse matrix (forjc,forir).
On input, n is number of columns.
------------------------------------------------------------ */
void getadj(mwIndex *forjc,mwIndex *forir,const mwIndex *cjc,const mwIndex *cir, mwSize n )
{
mwIndex i,j,inz,ix;
inz = 0;
for(j = 0; j < n; j++){
forjc[j] = inz + 1;
for(ix = cjc[j]; ix < cjc[j+1]; ix++)
if((i = cir[ix]) != j)
forir[inz++] = ++i;
}
forjc[n] = ++inz;
}
/* ============================================================
MAIN: MEXFUNCTION
============================================================ */
/* ************************************************************
PROCEDURE mexFunction - Entry for Matlab
perm = ordmmdmex(X) where X is symmetric sparse.
************************************************************ */
void mexFunction(const int nlhs, mxArray *plhs[],
const int nrhs, const mxArray *prhs[])
{
mwSize m, iwsiz;
mwIndex i, nofsub;
mwIndex *Xjc,*Xir,*iwork,*xadj,*adjncy,*perm,*invp;
mwSignedIndex flag;
double *permPr;
/* ------------------------------------------------------------
Check for proper number of arguments
------------------------------------------------------------ */
mxAssert(nrhs == 1, "ordmmd requires 1 input argument.");
mxAssert(nlhs == 1, "ordmmd generates 1 output argument.");
/* ------------------------------------------------------------
Check input X
------------------------------------------------------------ */
mxAssert(mxIsSparse(X_IN), "Input matrix must be sparse");
m = (int) mxGetM(X_IN);
mxAssert( m == (int) mxGetN(X_IN), "X should be square.");
/* ------------------------------------------------------------
Get input X
------------------------------------------------------------ */
Xjc = mxGetJc(X_IN);
Xir = mxGetIr(X_IN);
/* ------------------------------------------------------------
Create output vector PERM
------------------------------------------------------------ */
PERM_OUT = mxCreateDoubleMatrix(m, (mwSize)1, mxREAL);
permPr = mxGetPr(PERM_OUT);
/* ------------------------------------------------------------
Allocate working arrays:
int xadj(m+1), adjncy(Xnnz), perm(m), invp(m), iwork(iwsiz)
------------------------------------------------------------ */
xadj = (mwIndex*) mxCalloc(m+1,sizeof(mwIndex));
adjncy = (mwIndex*) mxCalloc(Xjc[m],sizeof(mwIndex));
perm = (mwIndex*) mxCalloc(m,sizeof(mwIndex));
invp = (mwIndex*) mxCalloc(m,sizeof(mwIndex));
iwsiz = 4 * m;
iwork = (mwIndex*) mxCalloc(iwsiz,sizeof(mwIndex));
/* ------------------------------------------------------------
Convert C-style symmetric matrix to adjacency structure
(xadj,adjncy) in Fortran-style.
------------------------------------------------------------ */
getadj(xadj,adjncy,Xjc,Xir,m);
/* ------------------------------------------------------------
Compute multiple minimum degree ordering (J. Liu, in Fortran)
------------------------------------------------------------ */
ordmmd_(&m,xadj,adjncy, invp,perm, &iwsiz,iwork, &nofsub, &flag);
if(flag == -1)
mexErrMsgTxt("Error in ordmmd.");
/* ------------------------------------------------------------
Convert PERM to floating point.
------------------------------------------------------------ */
for(i = 0; i < m; i++)
permPr[i] = perm[i];
/* ------------------------------------------------------------
Release working arrays
------------------------------------------------------------ */
mxFree(iwork);
mxFree(invp);
mxFree(perm);
mxFree(xadj);
mxFree(adjncy);
}

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