linear algebra - LAPACK Matrix multiplication with C++ -

i new c++ , trying use lapack libraries matrix multiplication. tried run routine dgemm give below. expecting output a*b. every time answer b*a. way routine works or wrong code.

my code:

#include "stdafx.h" #include<iostream>  using namespace std;  extern "c" void dgemm_(const char *transa, const char *transb, const int *m, const int *n, const int *k, double *alpha, double *a, const int *lda, double *b, const int *ldb, double *beta, double *c, const int *ldc);  int main(void) {     double a[4] = {1,2,3,4};     double b[4] = {5,6,7,8};     char trans = 'n';     int m = 2;     int n = 2;     int k = 2;     double alpha = 1.0;     int lda = 2;     int ldb = 2;     double beta = 0.0;     double c[4];     int ldc = 2;      dgemm_(&trans, &trans, &m, &n, &k, &alpha, a, &lda, b, &ldb, &beta, c, &ldc);      cout << c[0] << endl;     cout << c[1] << endl;     cout << c[2] << endl;     cout << c[3] << endl;     getchar();     return 0; } 

any inputs helpful.

i've not studied details of call dgemm, , cannot tell how interpreting result matrix. seems pretty mixing col major , row major interpretations somewhere. calculation uses col major, assuming row major.