class SubMatrix implements Cloneable {

    public DataBlock row(final int r) {
        int beg = m_start + r * m_row_inc, end = beg + m_col_inc * m_ncols;
        return new DataBlock(m_data, beg, end, m_col_inc);
    }

    public  SubMatrix(final double[] data, final int nrows, final int ncols);
    public  SubMatrix(final double[] data, final int start, final int nrows,
            final int ncols, final int rowinc, final int colinc);
    public  SubMatrix(final SubMatrix m);

}