Re: [Rd] Bug in package stats function ar() (PR#10459)

From: Duncan Murdoch <murdoch_at_stats.uwo.ca>
Date: Sat, 24 Nov 2007 16:08:31 -0500

On 24/11/2007 11:45 AM, Ben Bolker wrote:

> 
> 
> Steven McKinney wrote:

>> Full_Name: Steven McKinney
>> Version: 2.6.0
>> OS: OS X
>> Submission from: (NULL) (142.103.207.10)
>>
>>
>>
>> Function ar() in package "stats" is showing
>> a quirky bug. Some calls to ar() run to
>> completion, others throw an error.
>>
>> The bug is reproducible by several people on different
>> machines, however, the ar() function itself ends
>> up throwing the error sporadically. Several calls to
>> ar() may be necessary to trip the error condition.
>>
>> Code to reproduce:
>>
>> x<-ts(c(-0.2052083,-0.3764986,-0.3762448,0.3740089,0.2737568,2.8235722,-1.7783313,0.2728676,-0.3273164),start=c(1978,3),frequency=4,end=c(1980,3))
>> # ar function
>> res.ar<-ar(x,aic=TRUE,demean=F)
>> # call "ar" again and ............
>> res.ar<-ar(x,aic=TRUE,demean=F)
>>
>>
>> Example output:
>> (Note that on this attempt the first call to ar()
>> tripped the error.)
>>
>>> x<-ts(c(-0.2052083,-0.3764986,-0.3762448,0.3740089,0.2737568,2.8235722,-
>> +
>> 1.7783313,0.2728676,-0.3273164),start=c(1978,3),frequency=4,end=c(1980,3))
> 
>  Slightly more detail: in the "eureka" function, in stats/src/eureka.f, the
> last
> element of "vars" in the return list is bogus and varies among calls; if it
> comes out to NaN or NA it triggers the bug.
> 
>   Haven't spent any more time yet tracking this down, but hope that
> will save someone a few minutes.

Thanks, I'll take a look.

Duncan Murdoch



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