2 research outputs found
Pseudo-random number generators for Monte Carlo simulations on Graphics Processing Units
Basic uniform pseudo-random number generators are implemented on ATI Graphics
Processing Units (GPU). The performance results of the realized generators
(multiplicative linear congruential (GGL), XOR-shift (XOR128), RANECU, RANMAR,
RANLUX and Mersenne Twister (MT19937)) on CPU and GPU are discussed. The
obtained speed-up factor is hundreds of times in comparison with CPU. RANLUX
generator is found to be the most appropriate for using on GPU in Monte Carlo
simulations. The brief review of the pseudo-random number generators used in
modern software packages for Monte Carlo simulations in high-energy physics is
present.Comment: 31 pages, 9 figures, 3 table
Universal persistence exponents in an extremally driven system
The local persistence R(t), defined as the proportion of the system still in
its initial state at time t, is measured for the Bak--Sneppen model. For 1 and
2 dimensions, it is found that the decay of R(t) depends on one of two classes
of initial configuration. For a subcritical initial state, R(t)\sim
t^{-\theta}, where the persistence exponent \theta can be expressed in terms of
a known universal exponent. Hence \theta is universal. Conversely, starting
from a supercritical state, R(t) decays by the anomalous form 1-R(t)\sim
t^{\tau_{\rm ALL}} until a finite time t_{0}, where \tau_{\rm ALL} is also a
known exponent. Finally, for the high dimensional model R(t) decays
exponentially with a non--universal decay constant.Comment: 4 pages, 6 figures. To appear in Phys. Rev.