CUBLAS matrix multiplication

Question

After implementing matrix multiplication with CUDA. I tried to implement it with CUBLAS(thanks to the advice of some people here in the forum).

I can multiply square matrices but (yes once again...) I am having difficulties working with non square matrices. The only type of non square matrix multiplication that works is when you vary Matrix A's Width(A*B=C).

I don't get any errors but the resulting matrix returns wrong values. Here is my code(it is basically an adaptation of the simpleCUBLAS SDK example):

#include <stdlib.h>
#include <stdio.h>
#include "cublas.h"
#define HA 2
#define WA 9
#define WB 2
#define HB WA 
#define WC WB   
#define HC HA  
#define index(i,j,ld) (((j)*(ld))+(i))

void printMat(float*P,int uWP,int uHP){
//printf("\n %f",P[1]);
int i,j;
for(i=0;i<uHP;i++){

    printf("\n");

    for(j=0;j<uWP;j++)
        printf("%f ",P[index(i,j,uHP)]);
        //printf("%f ",P[i*uWP+j]);
}
}




 int  main (int argc, char** argv) {
    cublasStatus status;
        int i,j;
        cublasInit();

        float *A = (float*)malloc(HA*WA*sizeof(float));
        float *B = (float*)malloc(HB*WB*sizeof(float));
        float *C = (float*)malloc(HC*WC*sizeof(float));
    if (A == 0) {
        fprintf (stderr, "!!!! host memory allocation error (A)\n");
        return EXIT_FAILURE;
    }
    if (B == 0) {
        fprintf (stderr, "!!!! host memory allocation error (A)\n");
        return EXIT_FAILURE;
    }
    if (C == 0) {
        fprintf (stderr, "!!!! host memory allocation error (A)\n");
        return EXIT_FAILURE;
        }


        for (i=0;i<HA;i++)
     for (j=0;j<WA;j++)
        A[index(i,j,HA)] = (float) index(i,j,HA);   
        for (i=0;i<HB;i++)
     for (j=0;j<WB;j++)
        B[index(i,j,HB)] = (float) index(i,j,HB); 
    /*
    for (i=0;i<HA*WA;i++)
    A[i]=(float) i;
    for (i=0;i<HB*WB;i++)
    B[i]=(float) i;         */  


        float* AA; float* BB; float* CC;

    /*ALLOCATE ON THE DEVICE*/
    status=cublasAlloc(HA*WA,sizeof(float),(void**)&AA);
        if (status != CUBLAS_STATUS_SUCCESS) {
        fprintf (stderr, "!!!! device memory allocation error (A)\n");
        return EXIT_FAILURE;
        }

        status=cublasAlloc(HB*WB,sizeof(float),(void**)&BB);
        if (status != CUBLAS_STATUS_SUCCESS) {
        fprintf (stderr, "!!!! device memory allocation error (A)\n");
        return EXIT_FAILURE;
        }

        status=cublasAlloc(HC*WC,sizeof(float),(void**)&CC);
        if (status != CUBLAS_STATUS_SUCCESS) {
        fprintf (stderr, "!!!! device memory allocation error (A)\n");
        return EXIT_FAILURE;
        }

    /*SET MATRIX*/
        status=cublasSetMatrix(HA,WA,sizeof(float),A,HA,AA,HA);
        if (status != CUBLAS_STATUS_SUCCESS) {
        fprintf (stderr, "!!!! device memory allocation error (A)\n");
        return EXIT_FAILURE;
        }

        status=cublasSetMatrix(HB,WB,sizeof(float),B,HB,BB,HB);
        if (status != CUBLAS_STATUS_SUCCESS) {
        fprintf (stderr, "!!!! device memory allocation error (A)\n");
        return EXIT_FAILURE;
        }

    /*KERNEL*/
        cublasSgemm('n','n',HA,WB,WA,1,AA,HA,BB,HB,0,CC,HC);

        status = cublasGetError();
        if (status != CUBLAS_STATUS_SUCCESS) {
        fprintf (stderr, "!!!! kernel execution error.\n");
        return EXIT_FAILURE;
        }
        cublasGetMatrix(HC,WC,sizeof(float),CC,HC,C,HC);
        if (status != CUBLAS_STATUS_SUCCESS) {
        fprintf (stderr, "!!!! device read error (A)\n");
        return EXIT_FAILURE;
        }


    /* PERFORMANCE OUTPUT*/

    printf("\nMatriz A:\n");
    printMat(A,WA,HA);
    printf("\nMatriz B:\n");
    printMat(B,WB,HB);
    printf("\nMatriz C:\n");
    printMat(C,WC,HC);

        free( A );  free( B );  free ( C );
        status = cublasFree(AA);
        if (status != CUBLAS_STATUS_SUCCESS) {
        fprintf (stderr, "!!!! memory free error (A)\n");
        return EXIT_FAILURE;
        }
        status = cublasFree(BB);
        if (status != CUBLAS_STATUS_SUCCESS) {
        fprintf (stderr, "!!!! memory free error (B)\n");
        return EXIT_FAILURE;
        }
        status = cublasFree(CC);
        if (status != CUBLAS_STATUS_SUCCESS) {
        fprintf (stderr, "!!!! memory free error (C)\n");
    return EXIT_FAILURE;
    }

        /* Shutdown */
        status = cublasShutdown();
        if (status != CUBLAS_STATUS_SUCCESS) {
        fprintf (stderr, "!!!! shutdown error (A)\n");
        return EXIT_FAILURE;
        }

    if (argc > 1) {
        if (!strcmp(argv[1], "-noprompt") ||!strcmp(argv[1], "-qatest") ) 
        {
    return EXIT_SUCCESS;
        }
        } 
        else
        {
            printf("\nPress ENTER to exit...\n");
            getchar();
        }

return EXIT_SUCCESS;


  }

Any thoughts? Also, does anyone has a matrix multiplication implementation in CUBLAS that is working, so i could compare? Thanks in advance.

Answer 1

I don't understand why you think that code you posted doesn't work. When I compile and run it, the resulting executable produces the same output that I get if I enter the same matrices into matlab and compute the product of them.

CUBLAS is a FORTRAN BLAS, it expects inputs in column major order (and your code is column major ordered). If the results don't match what you want, you must be confusing column and row major ordering somewhere.