pro imf, min=mind, max=maxd, binsize=binsize, nbins=nbins
@common_blocks.inc
;on_error, 2
; plots imf. make sure to have read either particle massdensity or
; particle mass depending on which format your run had. 
; most enzo runs need particle massdensity
; select the types 
  massind = (where((*parti.names) eq 'particle mass'))[0]
  if parti.read[massind] ne 1 then begin
     print, 'please first read the "particle mass" or "particle massdensity" fields!'
     return
  endif
  typeind = where(*parti.names eq 'particle_type')

  if N_elements(mind) lt 1 then mind = 1e-4
  if N_elements(maxd) lt 1 then maxd = 1e3
  if N_elements(binsze) lt 1 and N_elements(nbins) lt 1 then binsize=.25


  if parti.type gt 0 then begin
     th = histogram((*parti.d[typeind[0]])[ind])
     print, N_elements(th), ' different types of particles found.'
     typeind = where(*parti.names eq 'particle_type')
     if typeind[0] gt -1 then begin
        nind = where((*parti.d[typeind[0]])[ind] eq parti.type)
        if nind[0] gt -1 then ind = ind[nind] else print, 'no matching particle types found'
     end else print, 'no field with name "particle_type" read'
  endif
  print, 'including, ', N_elements(ind), ' points'
  If N_elements(ind) lt 2 then ind = LINDGEN(N_ELEMENTS(*(parti.d[massind])))
  
  mh = histogram(alog10((*parti.d[massind])[ind]*get_unit('particle mass')), $
                 min=alog10(mind), max=alog10(maxd), binsize=binsize, nbins=nbins, locations=locs)
; debug purposes:
  v = mh
  x = locs
  WIDGET_CONTROL, draw_area, GET_VALUE=old_win
  window, 5
  minp = min(where(mh gt min(mh)))
  plot, 10^(locs), (mh) > 1, /xlog, /ylog, psym=10, $
        xtitle='mass ['+get_unit('particle mass', /ulabel)+']', ytitle='dN/dlog M'


  wset, old_win
  

END