docs: public static double elementMax( DMatrix6 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;
          if( a.a5 > max ) max = a.a5;
          if( a.a6 > max ) max = a.a6;
  
          return max;
      }