Emmanuel,

I'm not sure that I understand your message.
Does it mean that new walls will automatically follow your formula?
We won't need this spreadsheet model anymore?

EDIT
I constructed a semi-circle in v3.0 and imported it in v3.1b13. Then I constructed the same semi-circle in v3.1b13, and it lines up perfectly with the imported one. That suggests they are based on the same mathematical <?> principles.

Hans