Thanks Jim. Here are the following details:

I need to find the sum,
w=n*d1/2, fixed 
SUM [nCk* g(w,k)*g(w, n-k-1)].

Here the SUM is taken from k=1,2,..,n-1.

f1<-exp(-t^2/(2*r*(r+1)))*G(t,r-1)

G(x,r)=integrate(f1,0,x), where G(x,0)=1

So, G(x,r) is related to G(x,r-1) by the above relation with the constraint 
G(x,0)=1.

g(x,r)= G(x,r)*exp(-x^2/(2*(r+1)))

I have described what I want to do, in the above, if any further details is 
rquired just let me know.




________________________________
From: jim holtman <jholtman@gmail.com>

Cc: r-help@r-project.org
Sent: Sun, August 22, 2010 3:49:50 PM
Subject: Re: [R] Recursion problem

We replied once that your function Grx is not correct.  It will
recurse to an infinite depth because there is no condition to end the
calls.  I would expect that there would be some test at the beginning
of the function to see if it should be called again.  You need to
debug your function, or rewrite to compute what you want.  You have
not described the problem you are trying to solve, so no solution can
be provided.


>
>
> Hi,
>
>
> I wanted to compute the value of the function ifn at certain values of n. But 
I
> am receiving the following error when I was using the following code(given at
> the end).
>
> Error: evaluation nested too deeply: infinite recursion / 
>options(expressions=)?
>
> I feel that since the function Grx is recursively related, perhaps making the
> code too complicated too handle. Can anyone let me know if there is any other
> way to handle this problem?
>
>
> d1=10.5
> Grx<-function(x,r)
> {
> G0=Grx(x,0)
> G0=1;
> fu1<-function(t){exp(-t^2/(2*r*(r+1)))*Grx(x,r-1)}
> return(integrate(fu1,0,x)$value)
> }
>
> grx<-function(x,r)
> {
> Grx(x,r)*exp(-x^2/(2*(r+1)))
> }
>
> ifn<-function(n)
> {
> w=n*d1/2;S1=0;
> for(k in  1:(n-1))
> {
>  S1=S1+choose(n,k)*grx(w,k)*grx(w,n-k-1)
> }
> return(S1);
> }
>
> ifn(7)
>
> Thanks in advance.
>
> Shant
>
>
>
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>
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>



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

What is the problem that you are trying to solve?



      
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