R help - Sep 2007 - Factorial, L-moments, and overflows

Hi everyone,

In the package POT, there is a function that computes the L-moments of a given
sample (samlmu). However, to compute those L-moments, one needs to obtain the
total number of combinations between two numbers, which, by the way, requires
the use of a factorial. See, for example, Hosking (1990 , p. 113).

How does the function "samlmu" in the package POT avoids overflows?

I was trying to build from scratch a R function similar to "samlmu"
and ran into overflows (Just for my educational purposes :o) ). Is there a trick
that I am missing to avoid overflows in the factorial function?

Thank you very much for your time. 

Pedro N. Rodriguez
SSRN Homepage: http://ssrn.com/author=412141/ 
Homepage: http://www.pnrodriguez.com/

It sounds like you are using 'integers'.  Have you considered
'numeric' (floating point)?  You can always look at the function
'samlmu' to see what it does in this case.

On 9/16/07, Pedro.Rodriguez at sungard.com <Pedro.Rodriguez at
sungard.com> wrote:
> Hi everyone,
>
> In the package POT, there is a function that computes the L-moments of a
given sample (samlmu). However, to compute those L-moments, one needs to obtain
the total number of combinations between two numbers, which, by the way,
requires the use of a factorial. See, for example, Hosking (1990 , p. 113).
>
> How does the function "samlmu" in the package POT avoids
overflows?
>
> I was trying to build from scratch a R function similar to
"samlmu" and ran into overflows (Just for my educational purposes :o)
). Is there a trick that I am missing to avoid overflows in the factorial
function?
>
> Thank you very much for your time.
>
> Pedro N. Rodriguez
> SSRN Homepage: http://ssrn.com/author=412141/
> Homepage: http://www.pnrodriguez.com/
>
> ______________________________________________
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http://www.R-project.org/posting-guide.html
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>

-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem you are trying to solve?