FUNCTION dustem_compute_polsed,p_dim,stp,out_st=out_st,_extra=extra

;+
; NAME:
;    dustem_compute_polsed
; PURPOSE:
;    Computes an SED from a given Dustem spectrum
; CATEGORY:
;    Dustem
; CALLING SEQUENCE:
;    sed=dustem_compute_polsed(p_dim[,st=][,_extra=][,/help])
; INPUTS:
;    p_dim      = parameter values
; OPTIONAL INPUT PARAMETERS:

;    stp        = Dustem structure

; OUTPUTS:

;    sed         : computed SED for filters in !dustem_data
;    dustem_qsed : SED in Q
;    dustem_used : SED in U

; OPTIONAL OUTPUT PARAMETERS:

;    stp        = Dustem output structure

; 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_polsed'
  dustem_polsed=0.
  goto,the_end
ENDIF

IF not keyword_set(stp) THEN BEGIN

  dustem_activate_plugins,p_dim/(*(*!dustem_fit).param_init_values)

  stp=dustem_run(p_dim)

ENDIF

If keyword_set(result) THEN result=stp

fact = 1.e4*(*!dustem_HCD)/(4.*!pi)/(3.e8/1.e-6/(stp.polsed).wav)*1.e20/1.e7

P = stp.polsed.em_tot*fact;1.00e17/(4.*!pi) ;This is Polarized intensity P

stI = stp.sed.em_tot*fact;1.00e17/(4.*!pi)    ;This is Total intensity I

out=0.
Nwaves=(size(P))[1]

frac=P/stI

tes=where(finite(frac) eq 0)
frac(tes)=0.

;THIS LOOP IS WRONG AND DOES NOT MAKE SENSE 

;IF ptr_valid(!dustem_plugin) THEN BEGIN
scopes=tag_names((*!dustem_scope))
IF scopes[0] NE 'NONE' THEN BEGIN

FOR i=0L,n_tags(*!dustem_scope)-1 DO BEGIN   
    
    IF total(strsplit((*(*!dustem_scope).(i)),'+',/extract) EQ 'REPLACE_QSED') THEN BEGIN
        
        Q_spec=(*(*!dustem_plugin).(i))[*,1]
    ENDIF 
    
    IF total(strsplit((*(*!dustem_scope).(i)),'+',/extract) EQ 'REPLACE_USED') THEN BEGIN
        U_spec=(*(*!dustem_plugin).(i))[*,2]
    ENDIF
    
ENDFOR    

    

IF ~isa(Q_spec) && ~isa(U_spec) THEN polar_ippsi2iqu,stI,Q_spec,U_spec,frac,replicate(!dustem_psi,Nwaves) 

FOR i=0L,n_tags(*!dustem_scope)-1 DO BEGIN

    
    IF total(strsplit((*(*!dustem_scope).(i)),'+',/extract) EQ 'ADD_QSED') THEN BEGIN
        Q_spec+=(*(*!dustem_plugin).(i))[*,1]
    ENDIF
    
    IF total(strsplit((*(*!dustem_scope).(i)),'+',/extract) EQ 'ADD_USED') THEN BEGIN
        U_spec+=(*(*!dustem_plugin).(i))[*,2]
    ENDIF              
    

ENDFOR

P=sqrt(Q_spec^2+U_spec^2)

ENDIF

dustem_polsed = (*!dustem_data.qsed).values * 0.

if not isarray(P) THEN stop ;I don't understand this test. The only thing it can indicate is a problem with the dust parameters or the fortran executable. But in my opinion these tests would be  

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',/info
ENDELSE

ind_polsed=where((*!dustem_data.qsed).filt_names NE 'SPECTRUM',count_polsed)  

IF count_polsed NE 0 THEN BEGIN

  filter_names=((*!dustem_data.qsed).filt_names)(ind_polsed)

  spolsed=dustem_cc(stp.polsed.wav,P,filter_names,cc=cc)

  dustem_polsed[ind_polsed]=spolsed

ENDIF

;stop

;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.qsed).filt_names EQ 'SPECTRUM',count_spec) 
IF count_spec NE 0 THEN dustem_polsed(ind_spec)=interpol(P,stp.polsed.wav,(((*!dustem_data.qsed).wav)(ind_spec)))

out_st=stp

;clean pointers
heap_gc

the_end:

RETURN,dustem_polsed

END