code: public Planed normalize(Planed dest) {
          double invLength = 1.0 / Math.sqrt(a * a + b * b + c * c);
          dest.a = a * invLength;
          dest.b = b * invLength;
          dest.c = c * invLength;
          dest.d = d * invLength;
          return dest;
      }
docs: Normalize this plane and store the result in <code>dest</code>.
  
  @param dest
  will hold the result
  @return dest