void start_timer()
{
  if (!timer_on)
  {
    MPI_Barrier(MPI_COMM_WORLD);
    ticks = clock();
    wtime = MPI_Wtime();
    timer_on = 1;
  }
}

void resume_timer()
{
  if (!timer_on)
  {
    ticks = clock() - ticks;
    wtime = MPI_Wtime() - wtime;
    timer_on = 1;
  }
}

void stop_timer()
{
  if (timer_on)
  {
    ticks = clock() - ticks;
    wtime = MPI_Wtime() - wtime;
    timer_on = 0;
  }
}

void print_timer()
{
  if (timer_on)
  {
    stop_timer();
    printf("(%i) Elapsed Wtime: %14.6f s (%5.1f%% CPU)\n",
           proc_rank, wtime, 100.0 * ticks * (1.0 / CLOCKS_PER_SEC) / wtime);
    resume_timer();
  }
  else
    printf("(%i) Elapsed Wtime: %14.6f s (%5.1f%% CPU)\n",
           proc_rank, wtime, 100.0 * ticks * (1.0 / CLOCKS_PER_SEC) / wtime);
}