A new random-number generator for multispin Monte Carlo algorithms

Abstract

We develop a novel multispin coded random number generator algorithm to compute bits equal to 1 with probabilityp. Compared to previously used algorithms, this generator is at least equally fast and allows for an arbitrary accuracy of the computed probability without any significant increase in time. An explicit implementation of the algorithm is given for a Cray-1 vector computer, and the modifications for other machines are discussed. Finally, the algorithm is tested by computing the magnetization of the two-dimensional Ising model. The measured speed of the program is 57 million spin-flips per second. The agreement with theoretical values is found to remain very satisfying even when quite close (∼-0.5%) to the critical temperature.