FUNCTION dustem_compute_sed,p_dim,st,SED_spec,out_st=out_st,_extra=extra,wave0=wave0,help=help

;+
; NAME:
;    dustem_compute_sed
; PURPOSE:
;    Computes an SED from a given Dustem     trum
; CATEGORY:
;    Dustem
; CALLING SEQUENCE:
;    sed=dustem_compute_sed(p_dim[,st][,sed_spec][out_st][,_extra=][,/help][wave0=])
; INPUTS:
;    p_dim      = parameter values (used only if st is not provided)
; OPTIONAL INPUT PARAMETERS:
;    st        = Dustem output structure, if provided, overrides p_dim
;    wave0     = minimum wavelength for spectra (?)
; OUTPUTS:
;    sed       = computed SED for filters in !dustem_data
;    sed_spec  = computed spectrum
; OPTIONAL OUTPUT PARAMETERS:
;    out_st      = same as sed
; ACCEPTED KEY-WORDS:
;    help      = If set, print this help
; COMMON BLOCKS:
;    None
; SIDE EFFECTS:
;    None
; RESTRICTIONS:
;    The dustem idl wrapper must be installed
; PROCEDURE:
;    None
; EXAMPLES
;    
; MODIFICATION HISTORY:
;    Written by J.-Ph. Bernard
;    see evolution details on the dustem cvs maintained at CESR
;    Contact J.-Ph. Bernard (Jean-Philippe.Bernard@cesr.fr) in case of problems.
;-

IF keyword_set(help) THEN BEGIN
  doc_library,'dustem_compute_sed'
  dustem_sed=0.
  goto,the_end
ENDIF

IF not keyword_set(st) THEN BEGIN
    
  dustem_activate_plugins,p_dim/(*(*!dustem_fit).param_init_values),st  
  ;st=dustem_run(p_dim)
    
ENDIF

if not keyword_set(wave0) then wave0 = 0.

; Convert into MJy/sr/1d20

fact = 1.e4*(*!dustem_HCD)/(4.*!pi)/(3.e8/1.e-6/st.sed.wav)*1.e20/1.e7 ;this is correct despite the way it is presented (1.e4/1e.7*1e.20=1.e17 which is the factor to convert from ergs to Mega Janskys)
SED_spec = st.sed.em_tot * fact

;ADDING PLUGIN TO SPECTRUM----------------
scopes=tag_names((*!dustem_plugin))
IF scopes[0] NE 'NONE' THEN BEGIN
;IF ptr_valid(!dustem_plugin) THEN BEGIN
  for i=0L,n_tags(*!dustem_plugin)-1 do begin
    if total(strsplit((*(*!dustem_plugin).(i).scope),'+',/extract) eq 'ADD_SED') then SED_spec+=(*(*!dustem_plugin).(i).spec)[*,0]
  endfor
ENDIF
;------------------------------------------

if not isarray(SED_spec) THEN stop 
    
;COMPUTE THE MODEL SED

dustem_sed = (*(*!dustem_data).sed).values * 0.

IF !dustem_do_cc NE 0 AND !dustem_never_do_cc EQ 0 THEN BEGIN
  message,'DOING color correction calculations',/info
ENDIF ELSE BEGIN
  message,'SKIPPING color correction calculations: we take previous values of cc',/info
ENDELSE

ind_sed=where((*(*!dustem_data).sed).filt_names NE 'SPECTRUM' and (*(*!dustem_data).sed).wav gt wave0,count_sed)
IF count_sed NE 0 THEN BEGIN
  filter_names=((*(*!dustem_data).sed).filt_names)[ind_sed]
  ssed=dustem_cc(st.sed.wav,SED_spec,filter_names,cc=cc)  
  dustem_sed[ind_sed]=ssed
ENDIF ELSE BEGIN
  print,"**** WARNING **** NO FILTER defined in DATA for COLOUR CORRECTION" 
ENDELSE

;For spectrum data points, interpolate in log-log
;Linear interpolation leads to wrong values, in particular where few
;wavelengths points exist in the model (long wavelengths).
ind_spec=where((*(*!dustem_data).sed).filt_names EQ 'SPECTRUM',count_spec)
IF count_spec NE 0 THEN BEGIN
    dustem_sed[ind_spec]=interpol(SED_spec,st.sed.wav,(((*(*!dustem_data).sed).wav)[ind_spec]))
    ;dustem_sed(ind_spec)=10^interpol(alog10(spec),alog10(st.sed.wav),alog10((((*!dustem_data.sed).wav)(ind_spec))))
ENDIF
out_st=st

;clean pointers
heap_gc

the_end:

;VG : error in cc IRAS1 when no PAH 
; j=where(dustem_sed ne dustem_sed,count)
; if count gt 0 then dustem_sed[j]=0.
;stop
RETURN,dustem_sed

END