Edit: No one complained about the German question https://tex.stackexchange.com/questions/61549/natbib-biblatex-styling-help for two hours, so I'd like to clarify what our position is (the votes below aren't enough to interpret them as consensus).
The OP of “Using function calc in TikZ” doesn't seem to speak English well enough to ask an understandable and coherent question. I was tempted to ask him to pose the question in Portuguese, and then have have google translate (or someone on this site who speaks Portuguese and English) translate it. However, since this might set a precedent, I wanted to ask first what you think about that.
Do we accept questions in languages other than English? What is the stack overflow policy on that?
EDIT: Let me rephrase that question, so that it is less broad: If we get a question in English, were it is impossible to understand what the problem really is, is it acceptable to ask for an additional explanation in the native language of the user?