[R] strange behaviour of negative binomial

[Gabor Grothendieck]

dax42 <Dax42 <at> web.de> writes:

: 
: Dear list,
: 
: I ran into a strange behaviour of the pnbinom function - or maybe I 
: just made a stupid mistake.
: First thing is that pnbinom seems to be very slow. The other - more 
: interesting one - is that I get two different curves when I plot the 
: estimated density and the density given by pnbinom. Shouldn't it be the 
: same?
: This is only the case, I think, if I use the parameter size = 1. I just 
: tried it for size = 2 and the result seemed correct..
: 
: Anyways, this is what I tried:
: 
: #parameters
: proba<-0.001039302;
: s<-1;
: 
: #random numbers with this distribution
: dom<-rnbinom(10000,s,proba);
: 
: #first plot
: plot(ecdf(dom),do.points=FALSE);
: 
: #second plot
: x<-seq(0,8700,0.5);
: lines(x,pnbinom(x,s,proba),col="red");

There was a change in ecdf in R 2.1.0 so try the development version
of R and see if there still is a problem with that.

BTW, you can omit the trailing the semicolons.