Hi Samantha, It is quite likely that you are not doing something right when you are explicitly computing large factorials. There is probably a good asymptotic approximation that will simplify things for you. In my experience, there is seldom a need to explicitly compute factorials of integers. What is the real problem that you are trying to solve?
Ravi. ---------------------------------------------------------------------------- ------- Ravi Varadhan, Ph.D. Assistant Professor, The Center on Aging and Health Division of Geriatric Medicine and Gerontology Johns Hopkins University Ph: (410) 502-2619 Fax: (410) 614-9625 Email: rvarad...@jhmi.edu Webpage: http://www.jhsph.edu/agingandhealth/People/Faculty/Varadhan.html ---------------------------------------------------------------------------- -------- -----Original Message----- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of molinar Sent: Thursday, April 23, 2009 9:42 AM To: r-help@r-project.org Subject: Re: [R] large factorials Thank you everyone all of your posts were very helpful. I tried each one and I think I have about 10 new packages installed. The formula I need to calculate did not involve any logarithms but infinite summations of factorials, I'm sorry for not specifying. I read some things about using logarithms but I thought in my case I would have to do an e to the log and by doing that R still gave me the same problems with numbers over 170. But I was able to get it to work by using the last post about the rsympy packages. I tried downloading bc but I didn't know how to connect it to R, so R said "could not find function bc". Thanks again for all of your help. Samantha Gabor Grothendieck wrote: > > Also the R sympy package can handle this: > >> library(rSymPy) > Loading required package: rJava > >> factorial.sympy <- function(n) sympy(paste("factorial(", n, ")")) > >> # note that first time sympy is called it loads java, jython and >> sympy # but on subsequent calls its faster. So make a dummy call first. >> factorial.sympy(10) > [1] "3628800" > >> # code from earlier post defining factorial.bc to be inserted here > >> benchmark(replications=10, columns=c('test', 'elapsed'), > + bc=factorial.bc(500), > + sympy = factorial.sympy(500)) > test elapsed > 1 bc 2.17 > 2 sympy 0.09 > > See the rSymPy, r-bc and rbenchmark home pages: > http://rsympy.googlecode.com > http://r-bc.googlecode.com > http://rbenchmark.googlecode.com > > On Wed, Apr 22, 2009 at 3:21 PM, molinar <sky...@hotmail.com> wrote: >> >> I am working on a project that requires me to do very large factorial >> evaluations. On R the built in factorial function and the one I >> created both are not able to do factorials over 170. The first gives >> an error and mine return Inf. >> >> Is there a way to have R do these larger calculations (the calculator >> in accessories can do 10000 factorial and Maple can do even larger) >> -- >> View this message in context: >> http://www.nabble.com/large-factorials-tp23175816p23175816.html >> Sent from the R help mailing list archive at Nabble.com. >> >> ______________________________________________ >> 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. > > -- View this message in context: http://www.nabble.com/large-factorials-tp23175816p23197201.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ 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.
