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 <sky2k2 at 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.
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______________________________________________ R-help at 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.
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