In the 2 and 3 vector case it is possible do define a fairly simple sampling space where this is possible.
Consider the unit square where the sample space is the area where x+y <1. It generalizes to 3 dimensions with no difficulty. x= (0:100)/100 y= (0:100)/100 z=outer(x,y, function(x,y) 1-x-y) library(lattice) wireframe(z~x+y, data.frame(x=x,y=rep(y,each=101), z) ,zlim=c(0,1) , scales=list(arrows=FALSE)) So I think the OP _is_ asking for a _random_ variable drawn from a sample space in an n-dimensional hyper-"triangular pyramid", with base being the n-1 dimensional analogue of an equilateral regular triaggle and the height of the pyramid being some value that corresponds to a value of 1-(nthroot(of some sum( that I cannot state with clarity right now)) -- David. On Nov 22, 2014, at 8:01 AM, Boris Steipe wrote: > Of course they are random. But they can't all be randomly picked from [0,1). > By scaling them, one is effectively scaling the interval from which they are > picked. > > B. > Nb: the scaling procedure will work for any probability distribution. > > > > On Nov 22, 2014, at 10:54 AM, Ranjan Maitra <maitra.mbox.igno...@inbox.com> > wrote: > >> I don't understand this discussion at all. >> >> n random numbers constrained to have sum <=1 are still random. They are not >> all independent. >> >> That said, the original poster's question is ill=formed since there can be >> multiple distributions these random numbers come from. >> >> best wishes, >> Ranjan >> >> >> >> On Sat, 22 Nov 2014 10:29:18 -0500 Boris Steipe <boris.ste...@utoronto.ca> >> wrote: >> >>> These are contradictory requirements: either you have n random numbers from >>> the interval [0,1), then you can't guarantee anything about their sum >>> except that it will be in [0,n). Or you constrain the sum, then your random >>> numbers cannot be random in [0,1). You could possibly scale the random >>> numbers: >>> n <- 13 >>> x <- runif(n) >>> x <- x / sum(x) >>> x; sum(x) >>> >>> This will guarantee that their sum is 1 (to numerical accuracy), but your >>> numbers are then effectively drawn from the interval [0,2/n) for large n. >>> >>> B. >>> >>> >>> On Nov 22, 2014, at 9:29 AM, Ragia Ibrahim <ragi...@hotmail.com> wrote: >>> >>>> >>>> Dear all, >>>> I use R 3.1.1 for Windows. >>>> kindly how can I generate n number of random numbers with probability from >>>> [0,1] >>>> and their sum must not be more than one >>>> thanks in advance >>>> Ragia >>>> >>>> >>>> >>>> [[alternative HTML version deleted]] >>>> >>>> ______________________________________________ >>>> 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. >>> >>> ______________________________________________ >>> 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. >>> >> >> >> -- >> Important Notice: This mailbox is ignored: e-mails are set to be deleted on >> receipt. Please respond to the mailing list if appropriate. For those >> needing to send personal or professional e-mail, please use appropriate >> addresses. >> >> ____________________________________________________________ >> FREE ONLINE PHOTOSHARING - Share your photos online with your friends and >> family! >> Visit http://www.inbox.com/photosharing to find out more! >> >> ______________________________________________ >> 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. > > ______________________________________________ > 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. David Winsemius Alameda, CA, USA ______________________________________________ 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.