If I've noticed correctly, some of my comments seem to be deleted by somebody else. The first time I didn't pay attention to this event, but I believe it happened again here. I've asked OP in the comment to his question whether he assumes that $q<1$, and OP responded that this can be assumed. He further put this assumption into the body of the question.
Now I can only see the next comment of mine starting with
Then... but not the first two comments. Checking out the timeline of the post didn't help to realize what had happened. Perhaps, OP has deleted his own comment, but unlikely he could do this with mine. For sure, these comments were of a limited usefulness after the edit, but shall it mean the are to be deleted?
Edited: I've found this thread which as well hints upon the thing.