R devel - Nov 2004 - (PR#7393) Re: dhyper() does not allow non-integer values for

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On Wed, 24 Nov 2004 Erik.Jorgensen@agrsci.dk wrote:
>
> dhyper() does not allow non-integer values for input parameters m and n.
>
> this is in contrast to the other functions in the _hyper()
"family",
I would argue that the bug was in the other functions. If not, there is a=20
bug in the documentation, which gives no way to tell what the result=20
should mean for non-integer m, n, k.

 =09-thomas

>  # OK
>  dhyper(1,10,90,10)
>
>  # NaN
>  dhyper(1,10.5,90,10)
>
>  # OK
>  phyper(1,10,90,10)
>  phyper(1,10.5,90,10)
>
>  # OK
>  qhyper(0.71,10,90,10)
>  qhyper(0.71,10.5,90,10)
>
>  # OK
>  rhyper(1,10,90,10)
>  rhyper(1,10.5,90,10)
>
>
>
> # this "naive" version of dhyper() works
>
> dhyperx<-function(x,m,n,k,log=3DFALSE){
>       lp<-lchoose(m, x) + lchoose(n, k-x) - lchoose( m+n, k)
>       if (log) {lp} else {exp(lp)}
>       }
>
>  # OK
>  dhyperx(1,10,90,10)
>  dhyperx(1,10.5,90,10)
>
>
>
> Erik J=F8rgensen
> Danish Institute of Agricultural Sciences
>
>
>
> --please do not edit the information below--
>
> Version:
>  platform =3D i386-pc-mingw32
>  arch =3D i386
>  os =3D mingw32
>  system =3D i386, mingw32
>  status =3D
>  major =3D 2
>  minor =3D 0.1
>  year =3D 2004
>  month =3D 11
>  day =3D 15
>  language =3D R
>
> Windows XP Professional (build 2600) Service Pack 1.0
>
> Search Path:
>  .GlobalEnv, package:methods, package:stats, package:graphics,
> package:grDevices, package:utils, package:datasets, Autoloads, package:base
>
> ______________________________________________
> R-devel@stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>
Thomas Lumley=09=09=09Assoc. Professor, Biostatistics
tlumley@u.washington.edu=09University of Washington, Seattle
---1936847065-1111238301-1101309010=:193006--

tlumley@u.washington.edu writes:
> >
> > dhyper() does not allow non-integer values for input parameters m and
n.
> >
> > this is in contrast to the other functions in the _hyper()
"family",
> 
> I would argue that the bug was in the other functions. If not, there is
a> =20
> bug in the documentation, which gives no way to tell what the result=20
> should mean for non-integer m, n, k.

My initial reaction too (and surely it is not a bug that functions
behave inconsistently in regions where they are not documented to work
at all), but on the other hand, noninteger m,n do appear to give a
well-defined distribution, and perhaps there's a way of making sense
of it? I wouldn't think it corresponds to noncentral hypergeometric
distributions.

>  =09-thomas
(who is suddenly coming across in quoted-unreadable?)


-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk)             FAX: (+45) 35327907