Function dustem_plugin_modify_dust_pol, st, key=key, val=val, scope=scope, paramtag=paramtag, help=help

;+
; NAME:
;    dustem_plugin_modify_dust_pol
; PURPOSE:
;    Produces stokes emission parameters for the dust and synchrotron components
; CATEGORY:
;    DUSTEM Wrapper
; CALLING SEQUENCE:
;    dustem_create_stokes(st,key=key,val=val)
; INPUTS:
;
; OPTIONAL INPUT PARAMETERS:
;    key  = input parameter number
;    val  = input parameter value
; OUTPUTS:
;    out = array containing the stokes emission parameters associated to the dust/synchrotron component or a concatenated version for both
; OPTIONAL OUTPUT PARAMETERS:
;    None
; ACCEPTED KEY-WORDS:
;    help                  = if set, print this help
; COMMON BLOCKS:
;    None
; SIDE EFFECTS:
;    None
; RESTRICTIONS:
;    The dustem fortran code must be installed
;    The dustem idl wrapper must be installed
; PROCEDURE:
;    This is a dustem plugin
;-

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

IF keyword_set(scope) THEN BEGIN
    out=0.
    goto, the_scope
ENDIF 

IF keyword_set(paramtag) THEN BEGIN
    out=0.
    goto, the_paramtag
ENDIF 

; if not keyword_set(st) then begin
;     ;stop
;     IF  ptr_valid((*!dustem_fit).CURRENT_PARAM_VALUES) THEN BEGIN
;         p_di=(*(*!dustem_fit).CURRENT_PARAM_VALUES)
;         
;     ENDIF ELSE BEGIN
;               p_di=(*(*!dustem_fit).PARAM_INIT_VALUES)    
;           ENDELSE 
;               
;     st=dustem_run(p_di)      
; endif

psi=0.
smallp=1.

IF keyword_set(key) THEN BEGIN 
  ind1=where(key EQ 1,count1)
  ind2=where(key EQ 2,count2)
  IF count1 NE 0 THEN smallp=val[ind1[0]] ; setting smallp from pd - this is another polarization fraction (constant) that is applied to the total dust emission
  IF count2 NE 0 THEN psi=val[ind2[0]] & !dustem_psi = psi ; setting psi from pd.  !dustem_psi here helps for the plotting.   
ENDIF

fact = 1.e4*(*!dustem_HCD)/(4.*!pi)/(3.e8/1.e-6/((st.polsed).wav))*1.e20/1.e7
P=((st.polsed).em_tot)*fact
I=((st.sed).em_tot)*fact
    
Nwaves=(size(I))[1]

frac=P/I*smallp
tes=where(finite(frac) eq 0)
frac(tes)=0.

;psi_em = replicate(psi,Nwaves)

polar_ippsi2iqu,I,Q,U,frac,replicate(psi,Nwaves);psi_em  

out=fltarr(Nwaves,5) ; modified this. This is the only plugin that has this number of outputs.

degtorad = !pi/180

out[*,0]=I
out[*,1]=Q
out[*,2]=U
out[*,3]=frac
out[*,4]=0.5*atan(U,Q)/degtorad

the_scope:
scope='REPLACE_POLSED'

the_paramtag:
paramtag=['p','Psi (deg)']

return, out

the_end:

end