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mydtrsm_b.c
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mydtrsm_b.c
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#include "mex.h"
void printout(double *A, int M, int N);
double mysumdot(double *a, double *b);
double* subv(double *vect, int flag, int start, int end, int N);
void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[]){
mexPrintf("C PROGRAM START\n");
double *A, *y, *x;
int i, j, tmp, N;
double *a,*b;
/*para in: A, y*/
/*para out: x*/
/*mxget*/
A = mxGetPr(prhs[0]);
N = mxGetN(prhs[0]);
y = mxGetPr(prhs[1]);
plhs[0] = mxCreateDoubleMatrix(1,N,mxREAL);
x = mxGetPr(plhs[0]);
/*back*/
x[N-1] = y[N-1] / A[(N-1)*N+N-1];
for (i=N-2;i>=0;i--) {
a = subv(x, -1, i+1, N-1, N);
b = subv(A, i, i+1, N-1, N);
x[i] = (y[i] - mysumdot(a, b)) /A[i*N+i];
free(a);
free(b);
}
}
double newsubv(double *vect, int flag, int start, int end, int N) {
int i;
double tmp;
}
double mysumdot(double *a, double *b) {
double tmp=0;
int i;
for (i=1;i<a[0]+1;i++) {
tmp += a[i]*b[i];
}
return tmp;
}
double* subv(double *vect, int flag, int start, int end, int N) {
/*flag is row number*/
int i;
/*double tmp[end-start+2];*/
double *tmp = malloc((end-start+2)*sizeof(double));
tmp[0]=end-start+1;
if (flag==-1) {
/*1 dimension*/
for (i=0;i<end-start+1;i++) {
tmp[i+1] = vect[start+i];
}
}
else {
/*matrix*/
for (i=0;i<end-start+1;i++) {
tmp[i+1]=vect[(start+i)*N+flag];
}
}
return tmp;
}
void printout(double *A, int M, int N){
int i,j;
for (i=0;i<M;i++) {
for (j=0;j<N;j++) {
mexPrintf("%f ", A[j*M+i]);
}
mexPrintf("\n");
}
mexPrintf("\n");
}