# Ratio of huge products

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## Ratio of huge products

 Hello everybody, I have to compute something in this form: x = prod(a:b) / prod(c:d),    where: a < c and b < d and obviously: a < b and c < d I cannot make assumptions on the relative position of c,b and a,d. The problem is that a,b,c,d are large and the products are huge (R return Inf). Their ratio is less than 1 but significantly higher than 0: it is a non-tiny probability. I need to find a way to simplify this ratio. The only way to solve this that I see is to decompose into prime factors all the numbers in the numerator and the denominator and to remove the ones in common Do you know a better way to do this ? Thank you, Alberto ______________________________________________ [hidden email] mailing list https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code.
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## Re: Ratio of huge products

 Use logs? Michael On Thu, Dec 15, 2011 at 1:35 PM, Alberto Magni <[hidden email]> wrote: > Hello everybody, > > I have to compute something in this form: > > x = prod(a:b) / prod(c:d),    where: a < c and b < d and obviously: a > < b and c < d > > I cannot make assumptions on the relative position of c,b and a,d. > > The problem is that a,b,c,d are large and the products are huge (R return Inf). > Their ratio is less than 1 but significantly higher than 0: it is a > non-tiny probability. > > I need to find a way to simplify this ratio. > The only way to solve this that I see is to decompose into prime > factors all the > numbers in the numerator and the denominator and to remove the ones in common > > Do you know a better way to do this ? > > Thank you, > Alberto > > ______________________________________________ > [hidden email] 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. ______________________________________________ [hidden email] mailing list https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code.