if(g_proc_id == 0  && co < 20) {
if(g_proc_id == 0  && co < 20 && g_debug_level > 2) {
void update_fermion_momenta(double step, const int S) {  int i,mu;  double tmp;  su3adj *xm,*deriv;  double sum=0., max=0.;  double sum2=0.;  static int co = 0;  co++;  derivative_psf(S);#ifdef MPI  xchange_deri();#endif  for(i = 0; i < VOLUME; i++){    for(mu=0;mu<4;mu++){      xm=&moment[i][mu];      deriv=&df0[i][mu];      if(g_debug_level > 2) {	sum2 = _su3adj_square_norm(*deriv); 	sum+= sum2;	if(g_proc_id == 0  && co < 20) {	  printf("histogram%d %e\n",S,sum2);	  fflush(stdout);	}	if(sum2 > max) max = sum2;      }      /* This 2* is coming from what? */      tmp = 2.*step;      _minus_const_times_mom(*xm,tmp,*deriv);     }  }  if(g_debug_level > 0) {#ifdef MPI    MPI_Reduce(&sum, &sum2, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD);    sum = sum2;    MPI_Reduce(&max, &sum2, 1, MPI_DOUBLE, MPI_MAX, 0, MPI_COMM_WORLD);    max = sum2;#endif    if(g_proc_id == 0) {      printf("fermionforce%d %e max %e\n", S, sum/((double)(VOLUME*g_nproc))/4., max);      fflush(stdout);    }  }}