On 28-Sep-08 17:51:55, Uwe Ligges wrote: > Jörg Groß wrote: >> Hi, >> I tried to calculate the formula for the birthday problem >> (the probability that at least two people out of a group of >> n people share the same birthday) >> >> But the factorial-function allows me only to calculate >> factorials up to 170. >> >> So is there a way to push that limit? >> >> to solve this formula: >> >> (factorial(365) / factorial((365-23))) / (365^23) > > Obviously you can easily rewrite this formula to: > > prod(343:365) / (365^23) > > or > > factorial(23) * choose(365, 23) / (365^23) > > Uwe Ligges > >> (n=23)
I would put it in an even "safer" form: n <- 23 prod( ((365-(n-1)):365)/rep(365,n) ) In other word: It evaluates (343/365)*(344/365)* ... *(365/365) 365^N --> "Inf" if N > 120, whereas n<-150 prod( ((365-(n-1)):365)/rep(365,n) ) # [1] 2.451222e-16 Best wishes, Ted. -------------------------------------------------------------------- E-Mail: (Ted Harding) <[EMAIL PROTECTED]> Fax-to-email: +44 (0)870 094 0861 Date: 28-Sep-08 Time: 19:09:40 ------------------------------ 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.
