-
Notifications
You must be signed in to change notification settings - Fork 1
/
mydtrsm.c
65 lines (65 loc) · 1.64 KB
/
mydtrsm.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
#include "mex.h"
double* subv(double *vect, int flag, int start, int end, int N);
double mysumdot(double *a, double *b);
void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[]){
/*para in: A, b, pvt*/
/*para out: y*/
double *A, *b, *y, *x;
double *pvt, *va, *vb;
int i, tmp;
int flag;
int N;
A = mxGetPr(prhs[0]);
N = mxGetN(prhs[0]);
b = mxGetPr(prhs[1]);
pvt= mxGetPr(prhs[2]);
plhs[0] = mxCreateDoubleMatrix(1,N,mxREAL);
y = mxGetPr(mxCreateDoubleMatrix(1,N,mxREAL));
x = mxGetPr(plhs[0]);
/*forward*/
tmp = pvt[0]-1;
y[0] = b[tmp];
for (i=1;i<N;i++) {
tmp=pvt[i]-1;
va = subv(y, -1, 0, i-1, N);
vb = subv(A, i, 0, i-1, N);
y[i] = b[tmp] - mysumdot(va, vb);
free(va);
free(vb);
}
/*back*/
x[N-1] = y[N-1] / A[(N-1)*N+N-1];
for (i=N-2;i>=0;i--) {
va = subv(x, -1, i+1, N-1, N);
vb = subv(A, i, i+1, N-1, N);
x[i] = (y[i] - mysumdot(va, vb)) /A[i*N+i];
free(va);
free(vb);
}
}
double mysumdot(double *a, double *b) {
/*dot and sum*/
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) {
/*get sub vector from vector or matrix*/
int i;
double *tmp = malloc((end-start+2)*sizeof(double));
tmp[0]=end-start+1;
if (flag==-1) {
for (i=0;i<end-start+1;i++) {
tmp[i+1] = vect[start+i];
}
}
else {
for (i=0;i<end-start+1;i++) {
tmp[i+1]=vect[(start+i)*N+flag];
}
}
return tmp;
}