*from shell command line type: gradsc -blc "climo 1 1990 1999"
*or from grads command line: climo 1 1990 1999
*two ouput files, climo1.png and climo1.dat
function main(args)
month=subwrd(args,1)
ni=subwrd(args,2)
nf=subwrd(args,3)
n=ni
m=1
while (n<=nf)
  say n
  ctlname='/REANALYSIS/'n'/ctl/monthly/sfc/tmp.sfc'
  say ctlname
  'open 'ctlname
  if (n=ni)
    'ta=tmp(t='month')'
  else
    fb=1./n
    fa=1.-fb
    'ta='fa'*ta+'fb'*tmp(t='month')'
  endif
  'close 1'
  n=n+1
  m=m+1
endwhile
title='avg in month 'month' from 'ni' to 'nf
'd ta'
'set strsiz .25'
'set string 1 l'
'draw string .5 8.00 'title
'printim climo'month'.png'
'set fwrite climo'month'.dat'
'set gxout fwrite'
'd ta'
'disable fwrite'
quit