code: public Integer nextValue()
      {
          int x = 0;
          double t = 0.0;
          while (true)
          {
              t -= Math.log(rng.nextDouble()) / mean.nextValue();
              if (t > 1.0)
              {
                  break;
              }
              ++x;
          }
          return x;
      }
docs: {@inheritDoc}