I've encountered a problem using set region that makes me uneasy.
Should these two lines,
set region /y=35N:45N
let sst_np = sst[GX=xax_np,y=@AVE]
not give the same numerical results as these:
let sst_np = sst[GX=xax_np,y=35N:45N@AVE]
?? I avoided the latter because I thought it was harder on memory, no?
Well they give different results in the following script
Rob Scott
(hopefully someone may find it useful for doing point correlations)
! Description: get the point correlation of 1D SST field
!-------------------------------------------------------
set data coads_climatology
define axis/x=140E:130W:1/units=longitude/edges xax_np
!-------------------------------------------------------
! the following gets the wrong answer
!-------------------------------------------------------
set region /y=35N:45N
let sst_np = sst[GX=xax_np,y=@AVE]
!-------------------------------------------------------
! but this would make it work:
!
** let sst_np = sst[GX=xax_np,y=35N:45N@AVE]
**
!-------------------------------------------------------
!-------------------------------------------------------
! keep q fixed:
! move p in zonal direction, find acvf = <p q>
!-------------------------------------------------------
let q = sst_np[x=145W]
!-------------------------------------------------------
! setup NetCDF file to hold the answer
!-------------------------------------------------------
let dummy = x[GX=xax_np]
let/title="SST Autocovariance" acvf = (1/0) * x[GX=xax_np]
save/clobber/file=sst_acvf.cdf acvf
!-------------------------------------------------------
! for all p points, get acvf
! save to NetCDF (use RESHAPE to get it on the right grid)
! save to ASCII (for comparison)
!-------------------------------------------------------
repeat/k=1:5 (let p = sst_np[i=`k`]; go variance; \
LIST/FORMAT=(1X,E14.7)/FILE="sst_acvf.dat"/CLOBBER/NOHEAD covar ; \
LET acvf = reshape(covar,dummy[i=`k`]) ; \
SAVE/APPEND/FILE=sst_acvf.cdf acvf)
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