From ligges at statistik.uni-dortmund.de  Tue Dec 14 13:11:04 2004
From: ligges at statistik.uni-dortmund.de (ligges@statistik.uni-dortmund.de)
Date: Tue Dec 14 14:06:34 2004
Subject: [Rd] Bug on log.p argument with all stat function (PR#7420)
Message-ID: <20041214121104.4C0FF10E92@slim.kubism.ku.dk>

casadoj@ecc.es wrote:
> Dear R Developers:
> 
> I have been playing with R, release 2.0.1 for a week now and have detected =
> that all stat functions related to distribution probabilities have the same=
>  problem:
> 
> 1.- The log.p parameter of all distribution functions, when set to TRUE, re=
> turns a extrange value.
> 
> Accoding to the manual, when set to true, it should return log(p) probabili=
> ty. So to my understanding, setting to true this parameters is the same as =
> getting the LOG of the same function with this parameter set to false.
> 
> 
>>pt (1.1, 5, F, T)
> 
> [1] 0.8392746
> 
>>pt (1.1, 5, T, T)
> 
> [1] 0.5168608
> 
>>log(pt (1.1, 5, F, T))
> 
> [1] -0.1752173
> 
> 1.- The first line is the lower tail cumulative probability of a 1.1 on a S=
> tudent T distribution with 5 degrees of freedom.
> 2.- The second line is the lower tail cumulative probability of a 1.1 on a =
> Student T distribution with 5 degrees of freedom on a log scale
> 3.- The third line is the same as the second, but calculated mannually inst=
> ead of using the log.p parameters
> 
> Why line 2 and 3 do not return the same result?


Please NEVER submit bug reports twice, in particular not an unsensible one!

One time ncp = 1, one time ncp = 0, so what's that surprising?

Uwe Ligges


> Reciba un cordial saludo,
> =0D
> Jos=E9 Luis Casado Mart=EDnez
> ------------------------------------------------------------------
> European Computing Consultants
> C/ Hermanos Garc=EDa Noblejas, N=BA 39, 5=AA, N 1
> 28037 Madrid
> Telf.: 34-91-406 19 15. Fax: 34-91-406 19 16
> Movil: 34-607-750 316
> ------------------------------------------------------------------
> 
> 
> _____________________________________________________________________
> Mensaje analizado y protegido, tecnologia antivirus www.trendmicro.es
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-devel@stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel


[Rd] Bug on log.p argument with all stat function (PR#7420)
ligges@statistik.uni-dortmund.de