[Gretl-users] Time series interpolation

Hi, I'm new to gretl, so forgive my ignorance. I'm aware that gretl provides forecasting functionality, but I'm interested in using any of the time-series models in gretl (AR, ARIMA, GARCH, etc) to interpolate a section of unknown data. If I have something like this: Year Stock value 1950 215 1951 220 1952 200 1953 195 Then it is easy in gretl to predict the following years (1954, 1955, and so forth). But if I have something like this: Year Stock value 1950 215 1951 220 1952 200 1953 195 1956 190 1957 185 1958 170 1959 150 I then want to "predict" (or technically interpolate) the values for the years 1954 and 1955 (the stock value will probably be something between 195 and 190). Is this possible with gretl? If so, how? Peter