[R] outer(-x, x, pmin) cannot allocate

[Roger D. Peng]

Actually, I believe it's 8 bytes for double precision.

-roger

Berton Gunter wrote:
> David:
> 
> In general, this is not a good question to ask, as one needs to go into the
> bowels of R to find an answer.
> 
> But note that 8000 x 8000 x 4 bytes for double precision  = 256 mb. Now look
> at the code of outer(). Two vectors of this size are created = 512mb. Then
> copies of these must be created to be passed into pmin, I believe, as R
> passes by value. That's 1gb.
> 
> My guess is that "+", as an internal function, avoids the final doubling.
> 
> Corrections/clarifications by knowledgeable R experts cheerfully welcomed.
> I'm on thin ice here.
> 
> -- Bert Gunter
> Genentech Non-Clinical Statistics
> South San Francisco, CA
>  
> "The business of the statistician is to catalyze the scientific learning
> process."  - George E. P. Box
>  
>  
> 
> 
>>-----Original Message-----
>>From: r-help-bounces at stat.math.ethz.ch 
>>[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Brahm, David
>>Sent: Wednesday, December 22, 2004 12:11 PM
>>To: r-help at stat.math.ethz.ch
>>Subject: [R] outer(-x, x, pmin) cannot allocate
>>
>>R> x <- 0. + 1:8000
>>R> y <- outer(-x, x, pmin)
>>Error: cannot allocate vector of size 1000000 Kb
>>
>>Why does R need to allocate a gigabyte to create an 8000 x 
>>8000 matrix?
>>It doesn't have any trouble with outer(-x, x, "+").  Thanks.
>>
>>-- David Brahm (brahm at alum.mit.edu)
>>
>>Version:
>> platform = i686-pc-linux-gnu
>> arch = i686
>> os = linux-gnu
>> system = i686, linux-gnu
>> status = 
>> major = 2
>> minor = 0.1
>> year = 2004
>> month = 11
>> day = 15
>> language = R
>>
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> 
> 
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-- 
Roger D. Peng
http://www.biostat.jhsph.edu/~rpeng/