;+
; This procedure smooths a spectrum with a hanning filter.
;
; @keyword decimate {in}{optional}{type=boolean} If set, decimates by 2.
;
; @examples
; <pre>
;    getrec,1
;    show
;    hanning
;    show
; </pre>
;
; @uses <a href="decimate.html">decimate</a>
;
; @version $Id: hanning.pro,v 1.6 2005/05/30 04:03:43 bgarwood Exp $
;-

pro hanning,decimate=decimate

	; Do the smoothing first

        len = data_valid(!g.s[0])
        if len le 0 then begin
            message,'No data in primary data container, nothing to smooth',/info
            return
        endif
	oldarr = *!g.s[0].data_ptr
	newarr = oldarr
	for i=1,len-2 do begin
		newarr[i] = (oldarr[i-1]+oldarr[i+1])/4.0 + oldarr[i]/2.0
	end

	*!g.s[0].data_ptr = newarr

	if n_elements(decimate) ne 0 then decimate,2 $
	else if !g.frozen eq 0 then show
end