Question marks in the contribution tree

Question

Dear all,

I modelized a product few month ago, and now when I go to the contribution tree there are only "?" instead of the data. I checked the data of the process and they are all here; besides, even when creating a new product system, only question marks appear in the contribution tree.

Would any of you know where it may come from and how to solve this issue?

Thank you very much.

Best,

Answer 1

Hi Agathe,

this typically happens if you have a system where values are out of range, i.e. above the limits of the double precision value range (which is extremely large, 1.797693134862315E+308, see e.g. https://www.ibm.com/docs/en/idr/11.4.0?topic=types-numbers). And in a model, this can occur if you have a non-converging loop, e.g. you have a process that produces 1 kg of steel and needs 1.1 kg of its own steel, and delivers steel also to other processes. Such a loop will lead to in principle infinite values, which cannot be displayed (and are incorrect, in addition). This situation even happens if you have an input of 1kg of steel and output of 1kg, and deliver to other processes as well.

I hope this clarifies, best wishes,

Andreas