class DiffConstant extends AbstractSingleTsVariable {

    @Override
    public void data(TsPeriod start, DataBlock data) {
        TsPeriod s = new TsPeriod(start.getFrequency(), m_start);
        int del = start.minus(s);
        // raw implementation
        if (del < 0) {
            throw new TsException("Unexpected DConstant");
        }
        double[] g = generateMeanEffect(m_ur, del + data.getLength());
        data.copyFrom(g, del);
    }

    public  DiffConstant(BackFilter ur, Day start);

}