On 24-Nov-08 13:36:31, Mulazzani Fabio (Student Com06) wrote: > I have a problem with permutations functions in R > I just started using R so maybe it is an easy question > I need to obtain all the 9.somthingExp 157 permutations that can be > given from the number from 1 to 100 > > I wrote the following commands: > >> library(gregmisc) >>options(expressions=1e5) > cmat <- combinations(300,2) > dim(cmat) # 44850 by 2 >>permutations(n=100, r=100) > > Unfortunately at a certain point (after few minutes) I get the > following Error: > > Error: cannot allocate vector of size 609.1 Mb > > What can I do? > Thanks > Fabio
The first thing to do is to decide how long you are willing to wait! To an adequate approximation there are 10^158 of them. Simply to obtain them all (at a rate of 10^10 per second, which is faster than the CPU frequency of most desktop computers) would take 10^148 seconds, or slightly longer than 3*(10^140) years. Current estimates of the age of the Universe are of the order of 1.5*(10^10) years, so the Universe will have to last about 2*(10^130) times as long as it has already existed, before the task could be finished. So: why do you want to do this? Best wishes, Ted. -------------------------------------------------------------------- E-Mail: (Ted Harding) <[EMAIL PROTECTED]> Fax-to-email: +44 (0)870 094 0861 Date: 24-Nov-08 Time: 16:43:29 ------------------------------ XFMail ------------------------------ ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
