FUNCTION dustem_read_pol,dir_in,file,silent=silent,help=help

;+
; NAME:
;   dustem_read_pol
;
; PURPOSE:
;   reads information relating to the grain polarization parameters
;   from the corresponding .DAT file
;
; CATEGORY:
;    DustEMWrap, Distributed, LowLevel, Initialization
;
; CALLING SEQUENCE:
;   st=dustem_read_pol(dir_in,file)
;
; INPUTS:
;    dir_in  : directory with input file
;    file  : input file to be read
;
; OPTIONAL INPUT PARAMETERS:
;
; OUTPUTS:
;    st   : dustem data structure
;
; OPTIONAL OUTPUT PARAMETERS:
;
; ACCEPTED KEY-WORDS:
;    help     : writes this help
;
; COMMON BLOCKS:
;    None
;
; SIDE EFFECTS:
;
; RESTRICTIONS:
;    The DustEM fortran code must be installed
;    The DustEMWrap IDL code must be installed
;
; PROCEDURES AND SUBROUTINES USED:  
;
; EXAMPLES:
;
; MODIFICATION HISTORY:
;    Written VG (?)
;    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_read_pol'
   full_st=0.
   goto,the_end
ENDIF


  
st=''
Nmax=10000L
sts=strarr(Nmax)
openr,unit,dir_in+'data/'+file,/get_lun

;==read comments
str='' & first_char='#'
WHILE first_char EQ '#' DO BEGIN
  readf,unit,str
  first_char=strmid(str,0,1)
ENDWHILE

stv=str_sep(strtrim(strcompress(str),2),' ')
atresh=float(stv(0))
pstiff=float(stv(1))
plev=float(stv(2))
readf,unit,cteta0
readf,unit,npol

full_st={file:file,atresh:atresh,pstiff:pstiff,plev:plev,cteta0:cteta0,npol:npol}

close,unit
free_lun,unit

the_end:
return,full_st

END