Intel® oneAPI Math Kernel Library
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## sparse matrix multiplication problem

Beginner
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Hi,
Please help me to resolve the problem with the calculation of product of two sparse matrices stored in the CSR format.
The following program computes the product C = A * B and returns an incorrect result.

double a[] = {1,2,2,3,1,1,4};
double b[] = {1,2,3,4,5,1,4};
int ja[] = {1,2,1,2,3,2,3};
int ia[] = {1,3,6,8};
int jb[] = {1,2,1,2,3,2,3};
int ib[] = {1,3,6,8};
double* c = NULL;
int* jc = NULL, * ic = NULL;

int m = 3;
double beta = 1.0;
char trans = 'N';
int request, sort;
int info;

ic = new int[m+1];
request = 1; sort = 0;
mkl_dcsrmultcsr(&trans, &request, &sort, &m, &m, &m, a, ja, ia, a, ja, ia, c, jc, ic, NULL, &info);
c = new double[ic-1]; jc = new int[ic-1];
request = 2;
mkl_dcsrmultcsr(&trans, &request, &sort, &m, &m, &m, a, ja, ia, a, ja, ia, c, jc, ic, NULL, &info);

Results:
c =  5       8       2       8      14       7       2       7      17
ic = 1       4       7      10
jc =  1       2       3       1       2       3       1       2       3

A = { 1 2 0
2 3 1
0 1 4 }

B = { 1 3 0
2 4 1
0 5 4 }

C = { 5 8  2
8 14 7
2 7  17 }  (incorrect 2nd column)

Best Regards,
Stan

2 Replies
Employee
254 Views
Thanks for letting us know your problem. I'm now trying to reproduce the issue, and I will update you as soon as I have some results. Best, Zhang
Employee
254 Views
Hi, I figured out the problem. Your "b" array is incorrectly specified. It's not in the correct order for the CSR format. It should be {1,3,2,4,1,5,4}. Zhang