The film ``Pi'' is a study in madness and its partner, genius. A tortured, driven man believes (1) that mathematics is the language of the universe, (2) nature can be expressed in numbers, and (3) there are patterns everywhere in nature. If he can find the patterns, if he can find the key to the chaos, then he can predict anything--the stock market, for example. If the man is right, the mystery of existence is unlocked. If he is wrong, the inside of his brain begins to resemble a jammed stock ticker.