class DifferenceStationaryModelHelper {

    public static Matrix last(final int len, final int step) {
        int nc = len, nr = nc / step;
        Matrix J = new Matrix(nr, nc);
        for (int r = 0, c = step - 1; r < nr; ++r, c += step) {
            J.set(r, c, 1);
        }
        return J;
    }

    public  DifferenceStationaryModelHelper(final DataBlock y, final Matrix X, final Matrix transformation, final BackFilter difference);
    public  DifferenceStationaryModelHelper(final IModelProvider provider);

}