The SIAM/Oxford 100-Digit Challenge

Stan Wagon
Department of Mathematics, Macalester College, St. Paul, Minnesota

Abstract: Last February an attractive challenge was made by L. Trefethen (Oxford Univ.). He posed 10 problems in numerical computing (some with connections to physics), and challenged the math community (with a $100 prize) to get 10 digits of the answer to each problem. He said: "They're hard! If anyone gets 50 digits in total, I will be impressed." Trefethen severely underestimated the persistence of his audience and the power of modern software. Ninety-four teams from around the world responded; 20 of them achieved perfect scores of 100 digits. The problems were a lot of fun and I will discuss my team's solution to several of them. If you care to try your hand at one, here is #4:

What is the global minimum of

esin(50x) + sin(60ey) + sin(70sin(x)) + sin(sin(80y)) - sin(10(x + y)) + (1/4)(x2 + y2)?