static int fQB(realtype t, N_Vector y, N_Vector yB, N_Vector qBdot, 
               void *user_dataB)
{
  ProblemData d;

  d = (ProblemData) user_dataB;

  N_VScale_Parallel(-(d->dOmega), yB, qBdot);

  return(0);
}
CAMLprim value sunml_nvec_par_n_vscale(value vc, value vx, value vz)
{
    CAMLparam3(vc, vx, vz);
    N_VScale_Parallel(Double_val(vc), NVEC_VAL(vx), NVEC_VAL(vz));
    CAMLreturn (Val_unit);
}