pro pdf, va, mass=massw, binsize=binsize, obin=obin
@common_blocks.inc
if N_elements(binsize) ne 1 then binsize=.1
if not keyword_set(massw) then begin
   pd = hist1d(va, vol, binsize=binsize, obin=obin) 
   title = 'Volume weighted pdf. binsize:'+string(binsize)
end else begin
   pd = hist1d(va, mass, binsize=binsize, obin=obin) 
   title = 'Mass weighted pdf. binsize:'+string(binsize)
endelse
ind = where(pd gt 0.)
pd = pd[ind]
obin = obin[ind]
iplot, obin, pd, /ylog, TITLE=title

return
end