Please take a look at the comments related to this question. Dietrich Burde posted a comment which, in my opinion, should be an answer, be he thinks that perhaps the moderators will see it as a trivial answer. What do you think?

@JoséCarlosSantos The general SE philosophy is that comments are for improving posts, and that answers are for posting answers. According to this philosophy, comments which provide answers ought to be deleted.

However, I think that we are a lot more lax about that here.

My general inclination is not to delete comments which provide answers (as, indeed, my general philosophy is not to delete too many comments; note that moving long threads to chat is not deletion).

I would further argue that the comment posted there is a reference plus an epsilon of commentary, and would need to fleshed out some to be a real answer.

Of course, anyone is free to post that answer.