how extract a smaller array from the mother array according the lat and lon information?

hi,every one .
 now I want to write a ncl script that get a smaller region dataset from the
global fnl dataset (dss083.2 )..

stx=20 ; stx is the start dimension of lon
edx=40 ; edx is the end dimension of lon
sty=80 ; sty is the start dimension of lat
edy=120 ; edy is the end dimension of lat
partt_var = grb_file->TMP_3_SFC_10(sty:edy,stx:edx) ;extract the dataset

 it seems that partt_var can get the(20:40,80:120) child array of
 grb_file->TMP_3_SFC_10

Now I want to extract the child array according the lat and lon index
information directly,
 How can I do it?
I do this
stx=100 ; stx is the start lon degree
edx=140 ; edx is the end lon degree
sty= 20,5 ; sty is the start lat degree
edy=41,5 ; edy is the end lat degree
partt_var = grb_file->TMP_3_SFC_10(lat_3|sty:edy,lon_3|stx:edx) ;extract
the dataset

when I write the script shown as above,it shows error and said that can not
use it.

how to modify the script ?
thank you.

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Received on Sat Jul 3 08:00:17 2010