[Gretl-users] How to reference a separate time observations for a given time series in gretl?

Hi, is there a way how to reference a separate time observations for a given time series in gretl? For example, if I wish to compute a "recession" dummy, i.e. an indicator with 1, if in the two last periods there were negative growth rates and 0 otherwise? E.g. let's have this time series called X (below is some data, with the obs. number and growth rate) Obs. no X ln(X)-ln(X(-1)) 1 34296 2 30383 -0.121145488 3 28899 -0.050076249 4 27669 -0.04349434 5 26303 -0.050629652 6 26206 -0.003694609 7 26687 0.018188163 8 26424 -0.009903867 9 25458 -0.037242653 10 23749 -0.069489611 11 24709 0.039627125 12 25151 0.017730107 13 24431 -0.029044839 14 25740 0.052193384 15 26240 0.019238762 16 25999 -0.009226888 17 26420 0.016063223 18 25847 -0.021926759 19 25660 -0.007261181 20 24407 -0.050063383 21 25618 0.048425253 What command would generate the values of 1 for periods with two consequtive negative values in series? I.e. I would get this series: n/a n/a 1 1 1 1 0 0 1 1 0 0 0 0 0 0 0 0 1 1 0 Thanks, Vladimir