[ncl-talk] daily average

[WIND]

Dear all,
I'm dealing with the JRA four times per day grib data. And I want to average the four times data to get a daily data.
My script is listed below
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
fa=addfile("t.grib","r")
T=fa->TMP_GDSO_ISBL ;T(123,37,73,144) 
Tpj=new((/31,37,73,144/),float)
do j=0,30 
    do i=0,123 
        Tpj(j,:,:,:)=(T(i,:,:,:)+T(i+1,:,:,:)+T(i+2,:,:,:)+T(i+3,:,:,:))/4
    i=i+4
   j=j+1
   enddo;
enddo;

 the error goes synatx error and error in statement. How should I do to get the daily average?
Any help would be appreciated!
Sincerely,
Yan
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