But I am not (wasting my time)
As I told : only the first extrapolated value ... (and the rest of my blah-blah from that message)

And I am not introducing a system : MKRoxton asked for help and that is what he got - simple coding help. I never introduced a system anywhere. The rule of thumb for extrapolations is a simplified version of probability that extrapolated values are going to show correct "predicted" values, not a system. Sorry if you think that it is a system.

regards
mladen