Dziękuję bardzo!
There is currently one answer to this and all such questions about calculations, coordinating data between tasks, dynamically setting fields, etc.:
User-Defined Tools.
Send task data outside to any tool or language you wish, do what you want, and send new data back in.
Dan can't possibly code-in all of the variations that individuals want, so we need to make use of the tools he has put in to get customized results.
That said, this is not as simple as it sounds and we're always exchanging notes about what's missing and how things can be done more easily.
Szczęśliwego Nowego Roku,
Antek. ;)