code: public static void sort(DenseMatrix64F matrix, RowComparator comparator)
      {
          int len = matrix.numCols;
          quickSort(matrix.data, 0, matrix.numRows-1, len, comparator, new double[len], new double[len]);
      }
docs: MatrixSort is able to sort matrix rows when matrix is stored in one dimensional
  array as in DenseMatrix64F.
  
  <p>Sort is using Quick Sort algorithm.
  @param matrix
  @param comparator