#include <stdio.h>
#include <cblas.h>

#define m 5
#define n 4
#define kl 3
#define ku 2
#define lda 8

double A[] = {
        0.0, 0.0, 1.0, 2.0,
        0.0, 1.0, 2.0, 3.0,
        1.0, 2.0, 3.0, 4.0,
        2.0, 3.0, 4.0, 5.0,
        3.0, 4.0, 5.0, 0.0,
        4.0, 5.0, 0.0, 0.0,
        0.0, 0.0, 0.0, 0.0,
        0.0, 0.0, 0.0, 0.0
         };

double X[] =  {1.0, 2.0, 3.0, 4.0};
double Y[] =  {1.0, 0.0, 2.0, 0.0, 3.0, 0.0, 4.0, 0.0, 5.0, 0.0};

int main()
{
    int i, j;

    cblas_dgbmv(CblasRowMajor, CblasNoTrans, m, n, kl, ku, 2.0, A, lda, X, 1, 10.0, Y, 2);

    //for (i=0; i<3; ++i)  printf("%5.1f\n", y[i]);

    for (i=0; i<10; ++i)
        printf("%5.1f ", Y[i]);

    return 0;
}