docs: @Override
      public DoubleMatrix transpose()
      {
          int m = rows();
          int n = columns();
          ItemSupplier s = supplier;
          DoubleMatrix tr = getInstance(n, m);
          ItemConsumer c = tr.consumer;
          for (int i = 0; i < m; i++)
          {
              for (int j = 0; j < n; j++)
              {
                  c.set(j, i, s.get(i, j));
              }
          }
          return tr;
      }