ABSTRACT
Chaos theory is best illustrated by Lorenz’s (1963 and 1964) famous Butterfly Effect - the notion that a butterfly stirring the air in Hong Kong today can transform storm systems in New York next month. The effect was discovered accidentally by Lorentz in 1961. He was making a weather forecast and wanted to examine one sequence of greater length. He tried to make what he thought was a shortcut. Instead of starting the whole run over again, he started half way through. To give the computer its initial values, he typed the numbers from the earlier printout. The new run should therefore duplicate the old one, but it did not. Lorentz saw that his new weather forecast was diverging so rapidly from the previous run that within a few months all resemblance has disappeared. There had been no malfunction of the computer or the program. The problem lay in the number he had typed. In the computer six decimal places were stored: 0.506127, but to save time, and because he thought it was unessential, he printed a rounded-off number with just three decimals: 0.506.
