;+
; NAME:
;	makediff
; CALLING SEQUENCE:
	PRO makediff
;-
	root = filepath(root='/work/bernie','rawdata/raw') 
	mapfiles1 = dialog_pickfile( path=root, filter='skymap*.pph', /multiple )

	for i=1, n_elements(mapfiles1)-1 do begin
	setfilespec,mapfiles1[i]
	name=getfilespec(part='name')+'-diff.pph'
	stat = bin_read(mapfiles1[i],mapfile)
	stat = bin_read(mapfiles1[i-1],mapold)
	bad = where(mapold le -9999.0)
	if (bad[0] ne -1) then mapold[bad]=BadValue(mapold)
	bad = where(mapfile le -9999.0)
	if (bad[0] ne -1) then mapfile[bad]=BadValue(mapfile)
	mapfile=array_smooth(mapfile,3)
	mapold=array_smooth(mapold,3)
	
;	good = where(finite(mapold) eq 1)
	; only subtract finite values, NaNs will override
	
;	mapfile[good] = mapfile[good]-mapold[good]
;	mapfile[bad] = BadValue(mapfile)
;	overlap = where(finite(mapfile[good]) eq 0)	
	; this should make any value that has NaN in new map take on the value
	; given by the previous map
;	nlowval = min(mapold[overlap],/nan)
;	nhighval = max(mapold[overlap],/nan)
;	lowval = min(mapfile,/nan)
;	highval = max(mapfile,/nan)
;	print, 'mapold l / h: ',nlowval, nhighval
;	print, 'mapfile l/ h: ',lowval, highval
;	mapold[overlap] = bytscl(mapold[overlap], min=lowval,max=highval)

;	mapfile[overlap] = mapold[overlap]
	mapfile = mapfile-mapold
	; want to average out the values i dropped in all willy nilly
	bin_write, filepath(root=root,subdir='../diffodd', name), mapfile

	end
	
end