code: public static double elementMax( DMatrix4 a ) {
          double max = a.a1;
          if( a.a2 > max ) max = a.a2;
          if( a.a3 > max ) max = a.a3;
          if( a.a4 > max ) max = a.a4;
  
          return max;
      }
docs: <p>
  Returns the value of the element in the vector that has the largest value.<br>
  <br>
  Max{ a<sub>i</sub> } for all i<br>
  </p>
  
  @param a A vector. Not modified.
  @return The max element value of the matrix.