81 lines
2.2 KiB
C
81 lines
2.2 KiB
C
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/************************************************************************
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* mexschurfun(X,dd,options)
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* options = 1, add dd to the diagonal of X (a square matrix)
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* options = 2, add the scalar dd to X.
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************************************************************************/
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#include "mex.h"
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#include <math.h>
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/********************************************************************
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PROCEDURE mexFunction - Entry for Matlab
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*********************************************************************/
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void mexFunction(const int nlhs, mxArray *plhs[],
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const int nrhs, const mxArray *prhs[])
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{
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int n;
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double *X, *dd;
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int *irX, *jcX;
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int isspX, j, jn, k, kstart, kend, r;
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int options;
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double tmp, tmp2, ddtmp;
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if(nrhs < 2)
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mexErrMsgTxt("mexschurfun: requires at least 2 input arguments.");
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if(nlhs > 0)
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mexErrMsgTxt("mexschurfun: requires no output argument.");
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X = mxGetPr(prhs[0]);
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isspX = mxIsSparse(prhs[0]);
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if (isspX) {
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irX = mxGetIr(prhs[0]);
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jcX = mxGetJc(prhs[0]);
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}
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n = mxGetM(prhs[0]);
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if ( n != mxGetN(prhs[0]) )
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mexErrMsgTxt("X should be square.");
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dd = mxGetPr(prhs[1]);
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if (mxIsSparse(prhs[1]))
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mexErrMsgTxt("Sparse dd not supported by mexschurfun.");
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if (nrhs == 2) {
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options = 1;
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} else {
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options = (int) (*mxGetPr(prhs[2]));
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ddtmp = dd[0];
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}
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/********************************************************/
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if (options==1) {
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if (isspX) {
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for (j=0; j<n; j++) {
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kstart = jcX[j]; kend = jcX[j+1];
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for (k=kstart; k<kend; k++) {
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r = irX[k];
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if (r==j) { X[k] += dd[j]; break; }
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}
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}
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} else {
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for (j=0; j<n; j++) { jn = j*n; X[j+jn] += dd[j]; }
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}
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} else {
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if (isspX) {
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for (j=0; j<n; j++) {
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kstart = jcX[j]; kend = jcX[j+1];
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for (k=kstart; k<kend; k++) {
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r = irX[k];
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X[k] += ddtmp;
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}
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}
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} else {
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for (j=0; j<n; j++) {
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jn = j*n;
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for (k=0; k<n; k++) {
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X[k+jn] += ddtmp;
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}
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}
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}
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}
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return;
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}
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/************************************************************************/
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