docs: public static DMatrix5 extractRow( DMatrix5x5 a , int row , DMatrix5 out ) {
          if( out == null) out = new DMatrix5();
          switch( row ) {
              case 0:
                  out.a1 = a.a11;
                  out.a2 = a.a12;
                  out.a3 = a.a13;
                  out.a4 = a.a14;
                  out.a5 = a.a15;
              break;
              case 1:
                  out.a1 = a.a21;
                  out.a2 = a.a22;
                  out.a3 = a.a23;
                  out.a4 = a.a24;
                  out.a5 = a.a25;
              break;
              case 2:
                  out.a1 = a.a31;
                  out.a2 = a.a32;
                  out.a3 = a.a33;
                  out.a4 = a.a34;
                  out.a5 = a.a35;
              break;
              case 3:
                  out.a1 = a.a41;
                  out.a2 = a.a42;
                  out.a3 = a.a43;
                  out.a4 = a.a44;
                  out.a5 = a.a45;
              break;
              case 4:
                  out.a1 = a.a51;
                  out.a2 = a.a52;
                  out.a3 = a.a53;
                  out.a4 = a.a54;
                  out.a5 = a.a55;
              break;
              default:
                  throw new IllegalArgumentException("Out of bounds row.  row = "+row);
          }
          return out;
      }