extern "C" void zgemm_(char*, char*, int*, int*, int*, cdouble*, cdouble*, int*, cdouble*, int*, cdouble*, cdouble*, int*, int*);
void multiply(cdouble* AtimesB, cdouble* A, cdouble* B, int msize)
{
    int LWORK = msize, INFO=0;
    char N = 'N';
    cdouble alpha(1,0);
	cdouble betax(0,0);
    set_zero(AtimesB,cdouble(0,0),msize*msize);
    zgemm_(&N, &N, &msize, &msize, &msize, &alpha, A, &msize, B, &msize, &betax, AtimesB, &msize,&INFO);
    if(INFO != 0)
    {
        cout << "Complex matrix product: Error at zgemm. INFO: " << INFO<< endl;
        exit(1);
    }
}