FUNCTION dustem_plugin_synchrotron,key=key,val=val,scope=scope,paramtag=paramtag,paramdefault=paramdefault,help=help

;+
; NAME:

;    dustem_plugin_synchrotron

;

; PURPOSE:

;    DustEMWrap plugin to compute synchrotron emission

;

; CATEGORY:

;    DustEM, Distributed, Mid-Level, Plugin

;

; CALLING SEQUENCE:

;    synch=dustem_plugin_synchrotron([,key=][,val=])

;

; INPUTS:
;    None

;

; OPTIONAL INPUT PARAMETERS:
;    key  = input parameter number
;    val  = input parameter value

;

; OUTPUTS:
;    synch = synch spectrum (on dustem wavelengths)

;

; OPTIONAL OUTPUT PARAMETERS:

;    scope = scope of the plugin
;    paramdefault = default values of parameters
;    paramtag = plugin parameter names as strings

;

; ACCEPTED KEY-WORDS:
;    help                  = if set, print this help

;

; COMMON BLOCKS:
;    None

;

; SIDE EFFECTS:
;    None

;

; RESTRICTIONS:

;    The DustEMWrap IDL code must be installed

;

; PROCEDURE:

;    This is a DustEMWrap plugin

;

; EXAMPLES

;    dustem_init
;    vec=dustem_plugin_sychrotron(scope=scope)

;

; MODIFICATION HISTORY:

;    Written by JPB 2022 
;    Evolution details on the DustEMWrap gitlab.
;    See http://dustemwrap.irap.omp.eu/ for FAQ and help.  

;-

IF keyword_set(help) THEN BEGIN

  doc_library,'dustem_plugin_synchrotron'

  output=0.
  goto,the_end
ENDIF

;default values of input parameters
s=3           ;power spectrum of CR E distribution

A=1           ;Synchrotron radiation amplitude at 10 mm

psi=0.        ;default polarization angle

smallp=0.3;0.3    ;default polarization fraction

;scope='ADD_SED+ADD_POLSED'
scope='ADD_SED'

;paramtag=['s (plaw_index)','Amp','p','Psi (deg)']

paramtag=[textoidl('\alpha_{CR}'),'Amp','p',textoidl('\psi')+' [deg]']
paramdefault=[s,A,smallp,psi]

IF keyword_set(key) THEN BEGIN 

  ind1=where(key EQ 1,count1)
  ind2=where(key EQ 2,count2)
  ind3=where(key EQ 3,count3)

  ind4=where(key EQ 4,count4)

  IF count1 NE 0 then s=val[ind1[0]]
  IF count2 NE 0 then A=val[ind2[0]]

  IF count3 NE 0 then smallp=val[ind3[0]] 

  IF count4 NE 0 then psi=val[ind4[0]]

ENDIF

lambir=dustem_get_wavelengths()
Nwavs=n_elements(lambir)

cmic=3.e14
nu=cmic/lambir
lambir_ref=10000.

output=fltarr(Nwavs,3)

;following eqn is Deschenes et al 2008, eq 6
;output[*,0]=nu^(-(s+3.)/2.)

; following is Condon 1992 page 590 (in text)
output[*,0]=nu^((1.-s)/2.)

norm=interpol(output[*,0],lambir,lambir_ref)
output[*,0]=A*output[*,0]/norm

polar_ippsi2iqu,output[*,0],Q,U,replicate(smallp,Nwavs),replicate(psi,Nwavs)

output[*,1]=Q

output[*,2]=U

;stop

the_end:
RETURN,output
  
END