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Re: regridding and memory
Hi Benyang,
It turns out that this is due to a bug in @AVE regridding, where in some
cases the wrong range of indices is used in computing the average for
regridding. The bug is in versions 5.22 - 5.40 of Ferret. We have a fix
for it, which will be in the version 5.41 release. Here's a related report
and reply.
http://ferret.wrc.noaa.gov/Ferret/Mail_Archives/fu_2002/msg00132.html
The bug is is only with @AVE; other regridding transforms will give you
correct results.
Ansley Manke
Benyang Tang wrote:
> I don't know how to make sense of the following Ferret section.
>
> I did
> list topo1[x=100,y=100]
> three times. Every time the value changed; no calculation was performed on the variable.
>
> The first list was 32.39, which was incorrect.
> The second list was 4715, after I listed the variable topo1 in a range.
> The third list was back to 32.39, after memory resizing.
>
> Any suggestions? Thanks.
>
> Benyang Tang
>
> ========================================
> $ ferret -gif
> NOAA/PMEL TMAP
> FERRET v5.40
> Linux 2.4.3-12smp - 02/19/02
> 28-May-02 17:07
> yes? define axis/y=1:224:1/unit=meters oldY
> yes? define axis/x=1:360:1/unit=meters oldX
> yes? define grid/y=oldY/x=oldX oldG
> yes?
> yes? FILE/VAR=topo/GRID=oldG/FORMAT=stream/type=r4/swap "topog.dat"
> yes?
> yes? define axis/y=1:224:2/unit=meters newY
> yes? define axis/x=1:360:2/unit=meters newX
> yes? define grid/y=newY/x=newX newG
> yes?
> yes? define var topo1=topo[g=newG@ave]
> yes?
> yes? list topo1[x=100,y=100]
> VARIABLE : TOPO[G=NEWG@AVE]
> FILENAME : topog.dat
> X (METERS): 99
> Y (METERS): 99
> 32.39
> yes?
> yes? list topo1[x=98:102,y=98:102]
> VARIABLE : TOPO[G=NEWG@AVE]
> FILENAME : topog.dat
> SUBSET : 2 by 2 points (X (METERS)-Y (METERS))
> 99 101
> 50 51
> 99 / 50: 4715. 2782.
> 101 / 51: 24. 6.
> yes?
> yes? list topo1[x=100,y=100]
> VARIABLE : TOPO[G=NEWG@AVE]
> FILENAME : topog.dat
> X (METERS): 99
> Y (METERS): 99
> 4715.
> yes? set memory/size=100
> Cached data cleared from memory
> yes?
> yes? list topo1[x=100,y=100]
> VARIABLE : TOPO[G=NEWG@AVE]
> FILENAME : topog.dat
> X (METERS): 99
> Y (METERS): 99
> 32.39
--
Ansley Manke Pacific Marine Environmental Laboratory Seattle WA (206)526-6246
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