R help - Aug 2010 - handling recursion relation

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)*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(5)

Thanks in advance.

Shant



      
	[[alternative HTML version deleted]]

Look at your first function:

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)
}

It immediately calls itself for infinite recursion.  How did you
expect to stop it?  I would have expected some type of test before the
call.  I put a counter in and it was 1661 levels down in the call at
the error.

On Fri, Aug 20, 2010 at 9:33 AM, Shant Ch <sha1one at yahoo.com>
wrote:
> 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)*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(5)
>
> Thanks in advance.
>
> Shant
>
>
>
>
> ? ? ? ?[[alternative HTML version deleted]]
>
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>


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

What is the problem that you are trying to solve?