private static void makeGraph ( Function1D f )
   {
      double hi = f.valueAt(0);
      double lo = f.valueAt(0);
      int width = 0;
      for( int o = 0; o < MAXROWS; o++)
      {
         double n = f.valueAt(o);
         if(n > hi) hi = n;
         if(n < lo) lo = n;
      }

      for ( int i = 0 ; i < MAXROWS ; i++ )
      {
         System.out.printf("%5.1f %5.1f",(double)i,f.valueAt(i));
         double n = f.valueAt(i);
         if ( n < hi && n > lo) width = (int)(10* (f.valueAt(i))) + 28;
         if ( hi == n ) width = MAXWIDTH;
         if ( lo == n) width = 0;
         for ( int j = 0 ; j < width ; j++ ) System.out.print("+");
         System.out.println();
      }
   }