12,670 research outputs found
Sampling from the Hardcore Process
Partially Recursive Acceptance Rejection (PRAR) and bounding chains used in conjunction with coupling from the past (CFTP) are two perfect simulation protocols which can be used to sample from a variety of unnormalized target distributions. This paper first examines and then implements these two protocols to sample from the hardcore gas process. We empirically determine the subset of the hardcore process\u27s parameters for which these two algorithms run in polynomial time. Comparing the efficiency of these two algorithms, we find that PRAR runs much faster for small values of the hardcore process\u27s parameter whereas the bounding chain approach is vastly superior for large values of the process\u27s parameter
Fermions as Global Correction: the QCD Case
It is widely believed that the fermion determinant cannot be treated in
global acceptance-rejection steps of gauge link configurations that differ in a
large fraction of the links. However, for exact factorizations of the
determinant that separate the ultraviolet from the infrared modes of the Dirac
operator it is known that the latter show less variation under changes of the
gauge field compared to the former. Using a factorization based on recursive
domain decomposition allows for a hierarchical algorithm that starts with pure
gauge updates of the links within the domains and ends after a number of
filters with a global acceptance-rejection step. Ratios of determinants have to
be treated stochastically and we construct techniques to reduce the noise. We
find that the global acceptance rate is high on moderate lattice sizes and
demonstrate the effectiveness of the hierarchical filter.Comment: 36 pages, 9 figures; improved version to be published in
Comput.Phys.Commun., new results for the topological charge presented in
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Indirect test of M-S circuits using multiple specification band guarding
Testing analog and mixed-signal circuits is a costly task due to the required test time targets and high end technical resources. Indirect testing methods partially address these issues providing an efficient solution using easy to measure CUT information that correlates with circuit performances. In this work, a multiple specification band guarding technique is proposed as a method to achieve a test target of misclassified circuits. The acceptance/rejection test regions are encoded using octrees in the measurement space, where the band guarding factors precisely tune the test decision boundary according to the required test yield targets. The generated octree data structure serves to cluster the forthcoming circuits in the production testing phase by solely relying on indirect measurements. The combined use of octree based encoding and multiple specification band guarding makes the testing procedure fast, efficient and highly tunable. The proposed band guarding methodology has been applied to test a band-pass Butterworth filter under parametric variations. Promising simulation results are reported showing remarkable improvements when the multiple specification band guarding criterion is used.Peer ReviewedPostprint (author's final draft
Fully Adaptive Gaussian Mixture Metropolis-Hastings Algorithm
Markov Chain Monte Carlo methods are widely used in signal processing and
communications for statistical inference and stochastic optimization. In this
work, we introduce an efficient adaptive Metropolis-Hastings algorithm to draw
samples from generic multi-modal and multi-dimensional target distributions.
The proposal density is a mixture of Gaussian densities with all parameters
(weights, mean vectors and covariance matrices) updated using all the
previously generated samples applying simple recursive rules. Numerical results
for the one and two-dimensional cases are provided
A new rejection sampling method without using hat function
This paper proposes a new exact simulation method, which simulates a realisation from a proposal density and then uses exact simulation of a Langevin diffusion to check whether the proposal should be accepted or rejected. Comparing to the existing coupling from the past method, the new method does not require constructing fast coalescence Markov chains. Comparing to the existing rejection sampling method, the new method does not require the proposal density function to bound the target density function. The new method is much more efficient than existing methods for certain problems. An application on exact simulation of the posterior of finite mixture models is presented
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