[Rd] Problem with R >3.0.0

[Prof Brian Ripley]

On 21/08/2013 13:45, peter dalgaard wrote:
>
> On Aug 20, 2013, at 19:42 , Shelton, Samuel wrote:
>
>> Hi all,
>>
>> Thanks for getting back to me. We would like to move over to v3.0.0 on our
>> cluster so that we can build matrices larger than 46300*46300 (limit in R
>> <3.0.0)
>> but so far we can't get things to work with R v3.0.0 and higher. I am
>> trying to trouble shoot at the moment and I am now thinking that the
>> problem is actually with the diag function that has been rewritten in
>> version 3.0.0.
>>
>>
>> The problem is definitely with the diag function and it does not occur on
>> smaller matrices (20000*20000) and I think it maybe a bug.
>> This illustrates the problem:
>>
>> This was done on an iMac i5 with OSX 10.8.5 16GB Ram and with R 3.0.1 (but
>> I do see the same for 3.0.0). This does not occur when I run it with R
>> 2.15.2.
>>
>
>
> Thanks. I can condense this to
>
>> M <- matrix(1,23170,23170) ; diag(M) <- 0 ; range(colSums(M))
> [1] 23169 23169
>> M <- matrix(1,23171,23171) ; diag(M) <- 0 ; range(colSums(M))
> [1]     0 23170

A much faster check is to look at M[1:3, 1:3]

> and the fact that 2^14.5 is 23170.48 is not likely to be a coincidence...
>
> It is only happening with some of my builds, though. In particular, my MacPorts build of 3.0.1 does not have the problem on Snow Leopard, nor does the CRAN build of 3.0.0, still on Snow Leopard. It takes forever to check on a 4GB machine....

Note that does not use the diag() function but diag<-(), which is 
essentially unchanged since 2.15.x (the error detection was moved above 
an expensive calculation).

It works correctly on x86_64 Linux and Solaris.  I suspect a 
platform-specific issue in

         x[cbind(i, i)] <- value


-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
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