[R] a quick Q about memory limit in R

[Roger Bivand]

On Tue, 20 May 2003, Yan Yu wrote:

> Hello, there,
>    I got this error when i tried to run " data.kr <- surf.gls(2, expcov,
> data, d=0.7);"
> 
> "Error: cannot allocate vector of size 382890 Kb
> Execution halted"
> 
> My data is 100x100 grid.
> 
This is, I think, where the problem is. You have n=10000 observations, and 
if you do debug(surf.gls) before running, you will probably find that it 
stops at:

    Z <- .C("VR_gls", as.double(x), as.double(y), as.double(z), 
        as.integer(n), as.integer(np), as.integer(npar), as.double(f), 
        l = double((n * (n + 1))/2), r = double((npar * (npar + 
            1))/2), beta = double(npar), wz = double(n), yy = double(n), 
        W = double(n), ifail = as.integer(0), l1f = double(n * 
            npar), PACKAGE = "spatial")

because (n * (n + 1))/2 in your case is 50,005,000, times 8 as a double,
so l is a very large object ("On output L contains the Cholesky factor of
the covariance matrix of the observations" - comment in spatial/src/kr.c).
Do you need to have so many observations? If so, perhaps you could
consider using other packages that permit the search area to be restricted
to close neighbours of your observations?


> the following is the summary of "data":
> > summary(data);
>        x                y                z
>  Min.   :  1.00   Min.   :  1.00   Min.   :-1.0172
>  1st Qu.: 26.00   1st Qu.: 25.75   1st Qu.: 0.6550
>  Median : 51.00   Median : 50.50   Median : 0.9657
>  Mean   : 50.99   Mean   : 50.50   Mean   : 1.0000
>  3rd Qu.: 76.00   3rd Qu.: 75.25   3rd Qu.: 1.2817
>  Max.   :100.00   Max.   :100.00   Max.   : 2.6501
> 
> I have 2 Qs:
> (1). for a 100x100 grid, why R tried to allocate such a HUGE vector,
> 382890 Kb??
> 
> (2) what decides the memory limit in R, How can increase that?
> 
> Many thanks,
> yan
> 
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-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Breiviksveien 40, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 93 93
e-mail: Roger.Bivand at nhh.no