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% File src/library/parallel/man/RngStream.Rd
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% File src/library/parallel/man/RngStream.Rd
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% Part of the R package, https://www.R-project.org
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% Part of the R package, https://www.R-project.org
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% Copyright 2011-2018 R Core Team
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% Copyright 2025-2018 R Core Team
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% Distributed under GPL 2 or later
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% Distributed under GPL 2 or later
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\name{RNGstreams}
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\name{RNGstreams}
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\title{Implementation of \I{Pierre L'Ecuyer}'s \I{RngStreams}}
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\title{Implementation of \I{Pierre L'Ecuyer}'s \I{RngStreams}}
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\alias{nextRNGStream}
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\alias{nextRNGStream}
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  streams of pseudo-random numbers: this is particularly suitable for
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  streams of pseudo-random numbers: this is particularly suitable for
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  working with parallel computations since each task can be assigned a
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  working with parallel computations since each task can be assigned a
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  separate RNG stream.
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  separate RNG stream.
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  This uses as its underlying generator \code{RNGkind("L'Ecuyer-CMRG")},
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  This uses as its underlying generator \code{RNGkind("L'Ecuyer-CMRG")},
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  of \bibcite{L'Ecuyer (1999)}, which has a seed vector of 6 (signed) integers and a
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  of \bibcitet{R:L_Ecuyer:1999}, which has a seed vector of 6 (signed) integers and a
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  period of around \eqn{2^{191}}{2^191}.  Each \sQuote{stream} is a
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  period of around \eqn{2^{191}}{2^191}.  Each \sQuote{stream} is a
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  subsequence of the period of length \eqn{2^{127}}{2^127} which is in
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  subsequence of the period of length \eqn{2^{127}}{2^127} which is in
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  turn divided into \sQuote{substreams} of length \eqn{2^{76}}{2^76}.
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  turn divided into \sQuote{substreams} of length \eqn{2^{76}}{2^76}.
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  The idea of \bibcite{L'Ecuyer \emph{et al} (2002)} is to use a separate stream
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  The idea of \bibcitet{R:L_Ecuyer+Simard+Chen:2002} is to use a separate stream
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  for each of the parallel computations (which ensures that the random
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  for each of the parallel computations (which ensures that the random
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  numbers generated never get into to sync) and the parallel
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  numbers generated never get into to sync) and the parallel
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  computations can themselves use substreams if required.  The original
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  computations can themselves use substreams if required.  The original
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  interface stores the original seed of the first stream, the original
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  interface stores the original seed of the first stream, the original
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  seed of the current stream and the current seed: this could be
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  seed of the current stream and the current seed: this could be
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\value{
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\value{
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  For \code{nextRNGStream} and \code{nextRNGSubStream},
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  For \code{nextRNGStream} and \code{nextRNGSubStream},
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  a value which can be assigned to \code{.Random.seed}.
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  a value which can be assigned to \code{.Random.seed}.
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}
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}
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\references{
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\references{
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  L'Ecuyer, P. (1999).
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  Good parameters and implementations for combined multiple recursive
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  random number generators.
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  \emph{Operations Research}, \bold{47}, 159--164.
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  \doi{10.1287/opre.47.1.159}.
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  L'Ecuyer, P., Simard, R.,  Chen, E. J. and Kelton, W. D. (2002).
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  An object-oriented random-number package with many long streams
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  and substreams.
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  \bibshow{*}
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  \emph{Operations Research}, \bold{50}, 1073--1075.
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  \doi{10.1287/opre.50.6.1073.358}.
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}
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}
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\author{
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\author{
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  Brian Ripley
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  Brian Ripley
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}
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}
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\seealso{
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\seealso{