[R] qbeta function in R

[R. Michael Weylandt]

It's here (search the sources for the appropriately named qbeta.c) but
I can't guarantee you'll understand it easily: Martin Maechler (and
others) works hard to make these the best in the business, but that
performance comes at a price, here paid in opacity:

http://svn.r-project.org/R/trunk/src/nmath/qbeta.c

Michael

On Fri, Mar 9, 2012 at 3:08 PM, Anamika Chaudhuri <canamika at gmail.com> wrote:
> Hi David:
>
> Thanks, I actually realized it was error on my part. I didnt think there
> was a problem with R-code, just wanted to get a better understanding of the
> function qbeta.
>
> Anamika
>
> On Fri, Mar 9, 2012 at 3:04 PM, David Winsemius <dwinsemius at comcast.net>wrote:
>
>>
>> On Mar 9, 2012, at 2:48 PM, Anamika Chaudhuri wrote:
>>
>>  HI All:
>>>
>>> Does anyone know the code behind the qbeta function in R?
>>>
>>
>> Well, yes, but don't you think it would be wise to question whether your
>> code might be the problem rather than the R code?
>>
>>
>>  I am using it to calculate exact confidence intervals and I am getting
>>> 'NaN' at places I shouldnt be. Heres the simple code I am using:
>>>
>>> k<-3
>>>
>>>> x<-NULL
>>>> p<-rbeta(k,3,3)# so that the mean nausea rate is alpha/(alpha+beta)
>>>> min<-10
>>>> max<-60
>>>> n<-as.integer(runif(3,min,max)**)
>>>> for(i in 1:k)
>>>>
>>> + x<-cbind(x,rbinom(5,n[i],p[i])**)
>>>
>>
>> Isn't this going to make x get longer with each pass through the loop? I
>> think your parameter are then going to be interpreted as values of "x".
>> Looks like "user error" to me.
>>
>> --
>> David
>>
>>
>>
>>>> # Exact Confidence Interval
>>>>
>>>> l_cl_exact<-qbeta(.025, x, n-x+1)
>>>>
>>> Warning message:
>>> In qbeta(p, shape1, shape2, lower.tail, log.p) : NaNs produced
>>>
>>>> u_cl_exact<-qbeta(.975, x+1, n-x)
>>>>
>>> Warning message:
>>> In qbeta(p, shape1, shape2, lower.tail, log.p) : NaNs produced
>>>
>>>> x
>>>>
>>>    [,1] [,2] [,3]
>>> [1,]    8   12   14
>>> [2,]    5   15   13
>>> [3,]    5   12   12
>>> [4,]    8   21   12
>>> [5,]    8   14   12
>>>
>>>> n
>>>>
>>> [1] 10 36 31
>>>
>>>> l_cl_exact
>>>>
>>>          [,1]      [,2]      [,3]
>>> [1,] 0.44390454 0.2184996 0.2314244
>>> [2,] 0.04667766       NaN 0.2454760
>>> [3,] 0.05452433 0.1855618       NaN
>>> [4,] 0.44390454 0.4862702 0.1855618
>>> [5,] 0.10115053       NaN 0.2184996
>>>
>>> Thanks for your help.
>>> Anamika
>>>
>>>        [[alternative HTML version deleted]]
>>>
>>> ______________________________**________________
>>> R-help at r-project.org mailing list
>>> https://stat.ethz.ch/mailman/**listinfo/r-help<https://stat.ethz.ch/mailman/listinfo/r-help>
>>> PLEASE do read the posting guide http://www.R-project.org/**
>>> posting-guide.html <http://www.R-project.org/posting-guide.html>
>>> and provide commented, minimal, self-contained, reproducible code.
>>>
>>
>> David Winsemius, MD
>> West Hartford, CT
>>
>>
>
>        [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.