class SubMatrix implements Cloneable {

    public boolean isEmpty() {
        return getColumnsCount() <= 0 || getRowsCount() <= 0;
    }

    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);

}