1,898 research outputs found
Portable random number generators
Computers are deterministic devices, and a computer-generated random number is a contradiction in terms. As a result, computer-generated pseudorandom numbers are fraught with peril for the unwary. We summarize much that is known about the most well-known pseudorandom number generators: congruential generators. We also provide machine-independent programs to implement the generators in any language that has 32-bit signed integers-for example C, C++, and FORTRAN. Based on an extensive search, we provide parameter values better than those previously available.Programming (Mathematics) ; Computers
JWalk: a tool for lazy, systematic testing of java classes by design introspection and user interaction
Popular software testing tools, such as JUnit, allow frequent retesting of modified code; yet the manually created test scripts are often seriously incomplete. A unit-testing tool called JWalk has therefore been developed to address the need for systematic unit testing within the context of agile methods. The tool operates directly on the compiled code for Java classes and uses a new lazy method for inducing the changing design of a class on the fly. This is achieved partly through introspection, using Javaâs reflection capability, and partly through interaction with the user, constructing and saving test oracles on the fly. Predictive rules reduce the number of oracle values that must be confirmed by the tester. Without human intervention, JWalk performs bounded exhaustive exploration of the classâs method protocols and may be directed to explore the space of algebraic constructions, or the intended design state-space of the tested class. With some human interaction, JWalk performs up to the equivalent of fully automated state-based testing, from a specification that was acquired incrementally
Synthetic sequence generator for recommender systems - memory biased random walk on sequence multilayer network
Personalized recommender systems rely on each user's personal usage data in
the system, in order to assist in decision making. However, privacy policies
protecting users' rights prevent these highly personal data from being publicly
available to a wider researcher audience. In this work, we propose a memory
biased random walk model on multilayer sequence network, as a generator of
synthetic sequential data for recommender systems. We demonstrate the
applicability of the synthetic data in training recommender system models for
cases when privacy policies restrict clickstream publishing.Comment: The new updated version of the pape
Determining species tree topologies from clade probabilities under the coalescent
One approach to estimating a species tree from a collection of gene trees is
to first estimate probabilities of clades from the gene trees, and then to
construct the species tree from the estimated clade probabilities. While a
greedy consensus algorithm, which consecutively accepts the most probable
clades compatible with previously accepted clades, can be used for this second
stage, this method is known to be statistically inconsistent under the
multispecies coalescent model. This raises the question of whether it is
theoretically possible to reconstruct the species tree from known probabilities
of clades on gene trees. We investigate clade probabilities arising from the
multispecies coalescent model, with an eye toward identifying features of the
species tree. Clades on gene trees with probability greater than 1/3 are shown
to reflect clades on the species tree, while those with smaller probabilities
may not. Linear invariants of clade probabilities are studied both
computationally and theoretically, with certain linear invariants giving
insight into the clade structure of the species tree. For species trees with
generic edge lengths, these invariants can be used to identify the species tree
topology. These theoretical results both confirm that clade probabilities
contain full information on the species tree topology and suggest future
directions of study for developing statistically consistent inference methods
from clade frequencies on gene trees.Comment: 25 pages, 2 figure
On the Degree Growth in Some Polynomial Dynamical Systems and Nonlinear Pseudorandom Number Generators
In this paper we study a class of dynamical systems generated by iterations
of multivariate polynomials and estimate the degreegrowth of these iterations.
We use these estimates to bound exponential sums along the orbits of these
dynamical systems and show that they admit much stronger estimates than in the
general case and thus can be of use for pseudorandom number generation.Comment: Mathematics of Computation (to appear
Noise and chaos contributions in fast random bit sequence generated from broadband optoelectronic entropy sources
International audienceDuring the last 4 years, chaotic waveforms for random number generation found a deep interest within the community of analogue broadband chaotic optical systems. Earlier investigations on chaos-based RNG were proposed in the 90s and early 2000, however mainly based on piecewise linear (PL) 1D map, with bit rate determined by analog electronic processing capabilities to provide the PL nonlinear function of concern. Optical chaos came with promises for much higher bit rate, and entropy sources based on high complexity (high dimensional) continuous time (differential) dynamics. More specifically in 2009, Reidler et al. published a paper entitled "An optical ultrafast random bit generator", in which they presented a physical system for a random number generator based on a chaotic semiconductor laser. This generator is claimed to reach potentially the extremely high rate of 300 Gb/s. We report on analysis and experiments of their method, which leads to the discussion about the actual origin of the obtained randomness. Through standard signal theory arguments, we show that the actual binary randomness quality obtained from this method, can be interpreted as a complex mixing operated on the initial analogue entropy source. Our analysis suggests an explaination about the already reported issue that this method does not necessarily require any specific deterministic property (i.e. chaos) from the physical signal used as the physical source of entropy. The bit stream randomness quality is found to result from "aliasing" phenomena performed by the post-processing method, both for the sampling and the quantization operations. As an illustration, such random bit sequences extracted from different entropy sources are investigated. Optoelectronic noise is used as a non deterministic entropy source. Electro-optic phase chaotic signal, as well as simulations of its deterministic model, are used as deterministic entropy sources. In all cases, the extracted bit sequence reveals excellent randomness
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