code: public void setR(double R)
      {
          if(R <= 0 || Double.isNaN(R) || Double.isInfinite(R))
              throw new IllegalArgumentException("R must be positive, not " + R);
          this.R = R;
      }
docs: Sets the maximum allowed norm of the model. The
  original paper suggests values in the range 10<sup>x</sup> for <i>x</i>
  &isin; {0, 1, 2, 3, 4, 5}.
  @param R the maximum allowed norm for the model