47 lines
1.3 KiB
C
47 lines
1.3 KiB
C
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/************************************************************************
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* mexpertdiag(X,pertdiag)
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* add pertdiag to the diagonal of X (a square matrix)
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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, *pertdiag;
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int j,jn;
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if(nrhs != 2)
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mexErrMsgTxt("mexpertdiag: requires 2 input arguments.");
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if(nlhs > 0)
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mexErrMsgTxt("mexpertdiag: requires no output argument.");
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X = mxGetPr(prhs[0]);
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if (mxIsSparse(prhs[0]))
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mexErrMsgTxt("Sparse X not supported by mexpertdiag.");
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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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pertdiag = mxGetPr(prhs[1]);
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if (mxIsSparse(prhs[1]))
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mexErrMsgTxt("Sparse pertdiag not supported by mexpertdiag.");
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for (j=0; j<n; j++) {
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jn = j*n;
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X[j+jn] += pertdiag[j];
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}
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return;
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}
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/************************************************************************/
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