This looks like a bug to me, and is a bit hard to describe, but easy to
reproduce.
Basically, if RNGkind is saved as something other than the default, and if the
first
operation in a session is a set.seed(), the default is reverted to. Reproduce
by:
cafe-rozo> R --vanilla
R version 2.7.1 (2008-06-23)
Copyright (C) 2008 The R Foundation for Statistical Computing
ISBN 3-900051-07-0
R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type 'license()' or 'licence()' for distribution details.
R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.
Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.
> sessionInfo()
R version 2.7.1 (2008-06-23)
i386--netbsdelf
locale:
C
attached base packages:
[1] stats graphics grDevices utils datasets methods
base> set.seed(1); runif(1) # check the default
[1] 0.2655087> RNGkind("Mar")
> RNGkind()
[1] "Marsaglia-Multicarry"
"Inversion"> set.seed(1); runif(1) # now check again
[1] 0.006153224> set.seed(1) # save seed and RNGkind
> q("yes")
cafe-rozo> R
R version 2.7.1 (2008-06-23)
: etc
[Previously saved workspace restored]
> runif(1) # with a saved seed, Marsaglia-Multicarry is used
[1] 0.006153224> set.seed(1); runif(1)
[1] 0.006153224> q()
Save workspace image? [y/n/c]: n
cafe-rozo>
R version 2.7.1 (2008-06-23)
: etc
[Previously saved workspace restored]
> set.seed(1); runif(1) # saved RNGkind is ignored ...
[1] 0.2655087> RNGkind() # and overridden ...
[1] "Mersenne-Twister" "Inversion"> q("no")
cafe-rozo> R
R version 2.7.1 (2008-06-23)
: etc
[Previously saved workspace restored]
> RNGkind() # and wrongly reported!
[1] "Mersenne-Twister" "Inversion"> runif(1) # Note this is actually using Marsaglia-Multicarry
[1] 0.006153224>
Ray Brownrigg
Mathematics, Statistics and Computer Science
Victoria University of Wellington
Wellington, NZ
