docs: public static double elementMax( DMatrix3x3 a ) {
          double max = a.a11;
          if( a.a12 > max ) max = a.a12;
          if( a.a13 > max ) max = a.a13;
          if( a.a21 > max ) max = a.a21;
          if( a.a22 > max ) max = a.a22;
          if( a.a23 > max ) max = a.a23;
          if( a.a31 > max ) max = a.a31;
          if( a.a32 > max ) max = a.a32;
          if( a.a33 > max ) max = a.a33;
  
          return max;
      }