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extractA.c
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extractA.c

/* ************************************************************
% Apart = extractA(At,Ajc,blk0,blk1,blkstart[,blkstart2])
% EXTRACTA Fast alternative to
% Apart = At(blkstart(1):blkstart(2)-1,:).
% Instead of blkstart(2), it takes "blkstart2" (if supplied) or
% size(At,1)+1 (if neither blkstart(2) nor blkstart2) are available.
%
% Extract submatrix of
% A with subscripts "blkstart(1):blkstart(2)-1" and has its nonzeros per column
% bounded bij Ajc1:Ajc2. If Ajc1 = [] (Ajc2=[]) then start at column start
% (end at column end) of A.
%
% SEE ALSO partitA.
% ******************** INTERNAL FUNCTION OF SEDUMI ********************
function Apart = extractA(At,Ajc,blk0,blk1,blkstart[,blkstart2]) --
% 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 <string.h>
#include "mex.h"
#include "blksdp.h"
#define APART_OUT plhs[0]
#define NPAROUT 1
#define AT_IN prhs[0]
#define AJC_IN prhs[1]
#define BLK0_IN prhs[2]
#define BLK1_IN prhs[3]
#define BLKSTART_IN prhs[4]
#define NPARINMIN 5
#define BLKSTART2_IN prhs[5]
#define NPARIN 6
/* ************************************************************
PROCEDURE extractA
INPUT
Ajc1, Ajc2, Air,Apr, m - sparse N x m matrix, we only consider nonzeros
in Air[Ajc1[k]:Ajc2[k]-1], k=0:m-1.
ifirst - subscript of 1st entry, thus to be subtracted from A-subscripts
OUTPUT
Y - sparse n x m matrix, with sum(Ajc2-Ajc1) nonzeros.
************************************************************ */
void extractA(jcir Y, const mwIndex *Ajc1,const mwIndex *Ajc2,
const mwIndex *Air, const double *Apr, const mwIndex ifirst,
const mwIndex m)
{
mwIndex i,j,inz,ajnnz;
inz = 0;
for(j = 0; j < m; j++){
Y.jc[j] = inz;
ajnnz = Ajc2[j]-Ajc1[j];
memcpy(Y.pr + inz, Apr+Ajc1[j], ajnnz * sizeof(double));
memcpy(Y.ir + inz, Air+Ajc1[j], ajnnz * sizeof(mwIndex));
inz += ajnnz;
}
/* ------------------------------------------------------------
Close last column of Y, and subtract "ifirst" from its subscripts
------------------------------------------------------------ */
Y.jc[m] = inz;
for(i = 0; i < inz; i++)
Y.ir[i] -= ifirst;
}
/* ************************************************************
PROCEDURE mexFunction - Entry for Matlab
************************************************************ */
void mexFunction(int nlhs, mxArray *plhs[],
int nrhs, const mxArray *prhs[])
{
jcir At, Apart;
mwIndex i, m, njc, ifirst, n, ynnz, blk0,blk1;
mwIndex *Ajc;
const double *blkstartPr, *AjcPr;
bool isblk0negative;
/* ------------------------------------------------------------
Check for proper number of arguments
------------------------------------------------------------ */
mxAssert(nrhs >= NPARINMIN, "extractA requires more input arguments.");
mxAssert(nlhs <= NPAROUT, "extractA produces less output arguments.");
/* --------------------------------------------------
GET inputs At, blkstart, Ajc1, Ajc2
-------------------------------------------------- */
mxAssert(mxIsSparse(AT_IN), "At must be a sparse matrix.");
At.jc = mxGetJc(AT_IN);
At.ir = mxGetIr(AT_IN);
At.pr = mxGetPr(AT_IN);
m = mxGetN(AT_IN);
if(nrhs >= NPARIN){
n = (mwIndex) mxGetScalar(BLKSTART2_IN);
ifirst = (mwIndex) mxGetScalar(BLKSTART_IN);
}
else if(mxGetM(BLKSTART_IN) * mxGetN(BLKSTART_IN) ==2){
blkstartPr = mxGetPr(BLKSTART_IN);
ifirst = (mwIndex) blkstartPr[0];
n = (mwIndex) blkstartPr[1];
}
else
mxAssert(0==1, "blkstart size mismatch.");
n -= (ifirst--);
AjcPr = mxGetPr(AJC_IN);
mxAssert(m == mxGetM(AJC_IN), "Ablkjc size mismatch.");
njc = mxGetN(AJC_IN);
blk0 = (mwIndex) mxGetScalar(BLK0_IN); /* double to mwIndex */
if(blk0>0){
--blk0; /* Fortran to C */
isblk0negative=0;}
else
isblk0negative=1;
if(mxGetM(BLK1_IN) * mxGetN(BLK1_IN) != 1)
blk1 = njc; /*default to end */
else{
blk1 = (mwIndex) mxGetScalar(BLK1_IN); /* double to mwIndex (thus inf not allowed) */
mxAssert(blk1>0,"");
--blk1; /* Fortran to C */
}
/* ------------------------------------------------------------
Allocate mwIndex array blkstart Ajc(2*m)
------------------------------------------------------------ */
Ajc = (mwIndex *) mxCalloc(MAX(2*m,1), sizeof(mwIndex));
/* ------------------------------------------------------------
Convert Ajc from double to mwIndex:
------------------------------------------------------------ */
mxAssert(blk0 < njc, "Ablkjc size mismatches blk0.");
if(isblk0negative)
memcpy(Ajc,At.jc,m*sizeof(mwIndex)); /* default: start of column */
else
for(i = 0; i < m; i++){ /* to integers */
Ajc[i] = (mwIndex) AjcPr[m*blk0 + i];
}
mxAssert(blk1 >= 0, "blk1 must be positive.");
if(blk1 >= njc)
memcpy(Ajc+m,At.jc+1,m*sizeof(mwIndex)); /* default: end of column */
else
for(i = 0; i < m; i++){ /* to integers */
Ajc[m+i] = (mwIndex) AjcPr[blk1*m + i];
}
/* ------------------------------------------------------------
Apart = sparse(n,m,ynnz);
------------------------------------------------------------ */
ynnz = 0;
for(i = 0; i < m; i++)
ynnz += Ajc[m+i]-Ajc[i]; /* nnz(Apart(:,i)) */
APART_OUT = mxCreateSparse(n,m, ynnz,mxREAL);
Apart.jc = mxGetJc(APART_OUT);
Apart.ir = mxGetIr(APART_OUT);
Apart.pr = mxGetPr(APART_OUT);
/* ------------------------------------------------------------
The real job:
------------------------------------------------------------ */
extractA(Apart, Ajc,Ajc+m,At.ir,At.pr, ifirst, m);
/* ------------------------------------------------------------
Release working array
------------------------------------------------------------ */
mxFree(Ajc);
}

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