code: public int compareTo(MutableDouble anotherMutableDouble) {
      double thisVal = this.d;
      double anotherVal = anotherMutableDouble.d;
      return (thisVal < anotherVal ? -1 : (thisVal == anotherVal ? 0 : 1));
    }
docs: Compares two <code>MutableDouble</code> objects numerically.
  
  @param anotherMutableDouble the <code>MutableDouble</code> to be
  compared.
  @return Tthe value <code>0</code> if this <code>MutableDouble</code> is
  equal to the argument <code>MutableDouble</code>; a value less than
  <code>0</code> if this <code>MutableDouble</code> is numerically less
  than the argument <code>MutableDouble</code>; and a value greater
  than <code>0</code> if this <code>MutableDouble</code> is numerically
  greater than the argument <code>MutableDouble</code> (signed
  comparison).