Re: SAVE in EOF analysis

[Ansley Manke <Ansley.B.Manke@xxxxxxxx>]

Hi Boyin,
The EOF functions do a large matrix inversion and so they
do take time.  In general the size of the matrix is dimensioned
(NX*NY) by NT, which can quickly become quite large.
Saving the result is definitely a good idea, so that you have
the results to work with.

Ansley Manke

Boyin Huang wrote:

> Hi, ferreters:
>
> Is the ferret so slow in doing EOF analysis?
>
> Using the demo file for eof analysis:
>
> -------------------------------------------------------
> SET REGION/X=67w:1w/Y=11S:11N
> USE coads_climatology
> LET eof_xyfcn = eof_space(sst, 0.5)
> SAVE/CLOBBER/FILE=sst_clim_eof_space.cdf eof_xyfcn
>
> USE sst_clim_eof_space.cdf
> SET VIEW ul; fill/l=1/TITLE="eof 1" eof_xyfcn; go land
> -------------------------------------------------------
>
> Which works fine to me. Now I wish to have EOF in a
> larger domain, say 120E-70W and 40S-50N.
>
> I replaced set region by
> SET REGION/X=120e:70w/Y=40S:50N
> and added
> SET MEMORY/SIZE=260.(my computer memory is 1.5gb).
>
> I found that the ferret runs for ever (how long should
> I wait for?).
>
> I tried to diagnose the problem by typing these
> command lines interactively line by line, and found
> the problem is that the program was stuck by SAVE
> command.
>
> I then tried NOT to use the save command, but ferret
> says that the variable was not found.
>
> So, do we have to save EOF first, and the read and
> plot?
>
> How can I do the EOF analysis within a larger space
> domain and long time series? Say, simulated global SST
> with 200x100 grids for 1200 month, sst(200,100,1200).
>
> =====
> Boyin Huang
> The Center for Research on the Changing Earth System (CRCES)
> 10211 Wincopin Circle, Suite 240
> Columbia, Maryland 21044
> Tel. 410-992-5300/819 (O), 410-737-4557(H)
> Fax. 410-992-5944, Email. byh@crces.org
> http://byh.crces.org
>
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--
Ansley Manke  Pacific Marine Environmental Laboratory  Seattle WA