“Do you have to be miserable to be funny?” That’s the question at the center of Kevin Pollak’s documentary, signaling a somewhat different approach to the culture of comedy and comedians. (A veteran stand-up performer himself, Pollak also acts on TV and in films including The Usual Suspects.) With Robin Williams’ startling suicide still a fresh wound (the film is dedicated to him), it’s a fair question and a serious one. If comedy is tragedy plus time, is stand-up comedy a kind of higher math used to survive that equation?