Hi, I have two questions on working with nonstationary models with Dynare++. First, it seems that the detrending commends which work with Dynare are not accepted by Dynare++. Is my understanding correct? (this is not a major issue since one can rewrite the model directly into stationary form). But this leads to my second question. I have permanent productivity shocks in the model. The usual way is to include the shock into the growth rate, by which the model is normalized. For example, if log(Z_{t+1}/Z_{t}) = \mu + e1, we will use \mu+e1 as the normalizing factor. But then I canâ€™t plot the IRF because the shock dies in one period. Does anyone have any idea how to plot IRF for permanent shocks. Thank you.

indeed Dynare++ does not know how to automatically detrend variables

I am not sure to understand your second question. You should easily get the IRF of the detrended model. If you want the IRF of the original nonstationary model, then you have to program a little bit: compute the detrending factor at all dates, multiply the detrended IRFs by this factor, then plot the result
Thank you. Yes, I got to conclusion that I need some programming to renormalize it, the way you explained, and it worked well.