R help - Mar 2013 - NaNS Error Message

Hi,
I'm using R to do a series of calculation and I have gotten several
warnings that say "NaNS produced". Whatever I could read on line gives
me
an idea that this warning is produced when the number is use is a negative
log or otherwise mathematically problematic.
I'm getting this error while using factorial() and gamma () on strictly
positive numbers (always greater than zero).
Here is a snippet of my code:
k goes from 1 to a positive limit.
S is always 100.
Only positive values of n are allowed into the loop.

if(n>0)
{
while(k<=lim)
       {

         sn<-(S-n);snfact<-gamma(sn);
         sn2<-(2-n+S);sn2gam<-gamma(sn2);

         num<-(ngam*sn2gam);


         nk2<-(2+k-(2*n)+S);
         nk2gam<-gamma(nk2);
         den<-(k*nk2gam);
         prob<-(num/den);

         sum<-(as.numeric((k*prob))+sum);

         k<-k+1;
       }
}

The error message  received for every instance of this loop is :
In gamma(sn) : NaNs produced
In gamma(sn2) : NaNs produced
In gamma(nk2) : NaNs produced


Where am I going wrong?
Thanks for your help :)

	[[alternative HTML version deleted]]

Only positive values of n are allowed into the loop... 
More importantly, is n ever larger than 52??? Because that results in nk2<0
(for k=1) and undefined gamma(nk2). Same goes for sn, if n>100.
Next time you may also want to write a reproducible example!

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of Sahana Srinivasan
Sent: Dienstag, 26. M?rz 2013 16:25
To: r-help at r-project.org
Subject: [R] NaNS Error Message

Hi,
I'm using R to do a series of calculation and I have gotten several warnings
that say "NaNS produced". Whatever I could read on line gives me an
idea that this warning is produced when the number is use is a negative log or
otherwise mathematically problematic.
I'm getting this error while using factorial() and gamma () on strictly
positive numbers (always greater than zero).
Here is a snippet of my code:
k goes from 1 to a positive limit.
S is always 100.
Only positive values of n are allowed into the loop.

if(n>0)
{
while(k<=lim)
       {

         sn<-(S-n);snfact<-gamma(sn);
         sn2<-(2-n+S);sn2gam<-gamma(sn2);

         num<-(ngam*sn2gam);


         nk2<-(2+k-(2*n)+S);
         nk2gam<-gamma(nk2);
         den<-(k*nk2gam);
         prob<-(num/den);

         sum<-(as.numeric((k*prob))+sum);

         k<-k+1;
       }
}

The error message  received for every instance of this loop is :
In gamma(sn) : NaNs produced
In gamma(sn2) : NaNs produced
In gamma(nk2) : NaNs produced


Where am I going wrong?
Thanks for your help :)

	[[alternative HTML version deleted]]

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and provide commented, minimal, self-contained, reproducible code.

On 26-03-2013, at 16:25, Sahana Srinivasan <sahanasrinivasan.91 at
gmail.com> wrote:
> Hi,
> I'm using R to do a series of calculation and I have gotten several
> warnings that say "NaNS produced". Whatever I could read on line
gives me
> an idea that this warning is produced when the number is use is a negative
> log or otherwise mathematically problematic.
> I'm getting this error while using factorial() and gamma () on strictly
> positive numbers (always greater than zero).
> Here is a snippet of my code:
> k goes from 1 to a positive limit.
> S is always 100.
> Only positive values of n are allowed into the loop.
> 
> if(n>0)
> {
> while(k<=lim)
>       {
> 
>         sn<-(S-n);snfact<-gamma(sn);
>         sn2<-(2-n+S);sn2gam<-gamma(sn2);
> 
>         num<-(ngam*sn2gam);
> 
> 
>         nk2<-(2+k-(2*n)+S);
>         nk2gam<-gamma(nk2);
>         den<-(k*nk2gam);
>         prob<-(num/den);
> 
>         sum<-(as.numeric((k*prob))+sum);
> 
>         k<-k+1;
>       }
> }
> 
> The error message  received for every instance of this loop is :
> In gamma(sn) : NaNs produced
> In gamma(sn2) : NaNs produced
> In gamma(nk2) : NaNs produced
> 
This not reproducible code.
Where is ngam?
Where is k set to 1?
What value does n have?

Berend