Pi directed by Darren Aronofsky
Before The Matrix, there was Pi. You might recall his more famous film, Requiem for a Dream. Similar to his later film, he once again takes us on the journey of uncontrollable obsession. Before watching this film I would say not to take the logic or math being done too seriously - remember Darren didn't come out of school with a Ph.D. Instead, focus your attention on Max and how his reactions and need for mathematical answers in nature keep intensifying and make us uncomfortable at the same time. The musical score adds to and keeps us minutely aware of the anxiety.
Side note: It was all made under $60,000. That should already tell you the Darren and Matthew Libatique (director of photography) did a mind-blowing job at bringing their masterpiece to life.