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+PRO dustem_variational_study_readme,model=model,help=help,png=png,postscript=postscript
+
+;+
+; NAME:
+;    dustem_variational_study_readme
+; PURPOSE:
+;    This is an example of how to run a variational study on the dust model parameters with the dustem wrapper.
+; CATEGORY:
+;    Dustem
+; CALLING SEQUENCE:
+;    dustem_variational_study_readme[,model=][,/help][,/png][,/postscript]
+; INPUTS:
+;    None
+; OPTIONAL INPUT PARAMETERS:
+;    None
+; OUTPUTS:
+;    None
+; OPTIONAL OUTPUT PARAMETERS:
+;    None
+; ACCEPTED KEY-WORDS:
+;    model = Selects one of the dust mixture used by dustem
+;           'COMPIEGNE_ETAL2010' from Compiegne et al 2010 (default)
+;           'DBP90' from Desert et al 1990
+;           'DL01' from Draine & Li 2001
+;           'DL07' from Draine & Li 2007
+;    postscript = if set, plot is done in DUSTEM/Docs/Figures/Last_dustem_fit.ps
+;    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:
+;    None
+; EXAMPLES
+;    dustem_variational_study_readme,model='DBP90',/postscript
+;    dustem_variational_study_readme,model='COMPIEGNE_ETAL2010',/postscript
+; MODIFICATION HISTORY:
+;    Written by J.P. Bernard July 15 2021
+;    see evolution details on the dustem gitlab
+;    Contact J.-Ph. Bernard (Jean-Philippe.Bernard@irap.omp.eu) in case of problems.
+;-
+
+;This Readme shows how to run dustem from the wrapper
+
+IF keyword_set(help) THEN BEGIN
+  doc_library,'dustem_variational_study_readme'
+  goto,the_end
+ENDIF
+
+;loadct,13
+
+IF keyword_set(model) THEN BEGIN
+  use_model=strupcase(model)
+ENDIF ELSE BEGIN
+  use_model='COMPIEGNE_ETAL2010'    ;Default is last dustem model
+ENDELSE
+
+;== This just initializes dustem wrapper
+dustem_init,model=use_model
+!dustem_verbose=1
+!dustem_show_plot=1
+
+IF keyword_set(png) THEN BEGIN
+  dir_png=!dustem_dat+'/Figures/'
+  force_mkdir,dir_png
+ENDIF
+IF keyword_set(postscript) THEN BEGIN
+  dir_ps=!dustem_dat+'/Figures/'
+  force_mkdir,dir_ps
+ENDIF
+
+IF not keyword_set(dir) THEN BEGIN
+;  CASE getenv('DUSTEM_WHICH') OF
+  CASE !dustem_which OF
+    'DESERT':dir='DESERT_POST_ISO_MORE/'
+    'COMPIEGNE': dir='MC_DAT/'
+    'VERSTRAETE': dir='d_3.5/'
+    'VERSTRAETE': dir='LV_DAT/'
+    'WEB3p8': dir_in=!dustem_soft_dir
+    ELSE: dir='les_DAT/'
+  ENDCASE
+ENDIF
+;== The following structure contains the inputs to the model
+st_model=dustem_read_all(dir_in)
+
+;These are the values of G0 to be explored
+g0s=[1.,2.,5.,10.,100.,1000.]
+n_g0s=n_elements(g0s)
+
+win=0L
+window,win,title='DustemWrap Variational study'
+
+CASE use_model OF
+  'DBP90': pd = ['(*!dustem_params).G0'] ;This is the parameter description of G0 for models without gas parameters
+  'COMPIEGNE_ETAL2010': pd = ['(*!dustem_params).gas.G0'] ;This is the parameter description of G0 for models with gas parameters
+  'AJ13' : pd = ['(*!dustem_params).G0'] ;This is the parameter description of G0 for models without gas parameters
+ENDCASE
+
+FOR i=0L,n_g0s-1 DO BEGIN
+  iv = [g0s[i]]
+  dustem_init_parinfo,pd,iv
+  params=[g0s[i]]
+  st=dustem_run(params)
+  ;do the plot
+  cleanplot
+  xtit=textoidl('\lambda (\mum)')
+  ;=== same plot as in Compiegne et al. 2010
+  ytit=textoidl('\nuI_\nu^{em} (W/m^2/sr for N_H=1.e20 H/cm^2)')
+  tit='Dustem Emitted Intensity '+use_model+' G0='+strtrim(g0s[i],2)
+  yr=[1e-11,1.e-4]
+  xr=[1,5e3]
+  ;stop
+  dustem_plot_nuinu_em,st,yr=yr,/ysty,xr=xr,/xsty,/xlog,/ylog,title=tit,xtit=xtit,ytit=ytit
+  IF keyword_set(postscript) THEN BEGIN
+    file_ps=dir_ps+use_model+'_variational_study_nuinuem_G0='+strtrim(g0s[i],2)+'.ps'
+    spawn,'rm '+file_ps
+    previous_device=!d.name
+    set_plot,'PS'
+    device,filename=file_ps
+    !p.charsize=0.8
+    dustem_plot_nuinu_em,st,yr=yr,/ysty,xr=xr,/xsty,/xlog,/ylog,title=tit,xtit=xtit,ytit=ytit
+    device,/close
+    set_plot,previous_device
+    message,'Wrote '+file_ps,/continue
+  ENDIF
+
+ENDFOR
+
+;stop
+
+the_end:
+
+END
--
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