pro enlarge_boxes
  fin='glass_10x10x10'
  readnew,fin,h,'HEAD'
  readnew,fin,xin,'POS'
  xin[*,*] /= h.BOXSIZE
  Nin = TOTAL(h.npart,/int)
  
  Ndup = 10L
  fout='glass_100x100x100'
  
  Np = Ndup^3 * Nin
  x=fltarr(3,Np)

  i=0L
  FOR ix=0,Ndup-1 DO BEGIN
     FOR iy=0,Ndup-1 DO BEGIN
        FOR iz=0,Ndup-1 DO BEGIN
           FOR j=0L,Nin-1 DO BEGIN
              x[0,i] = (xin[0,j] + ix) / Ndup
              x[1,i] = (xin[1,j] + iy) / Ndup
              x[2,i] = (xin[2,j] + iz) / Ndup
              i++
           END
        END
     END
  END
  
  v = fltarr(3,Np)
  u=fltarr(Np)
  m=fltarr(Np)
  id=lindgen(Np)

  h.BOXSIZE=1
  h.MASSARR[*]=0

  gamma=5./3.
  rho=0.125
  P = 1.0
  
  u[*] = P/(gamma-1)/rho
  m[*] = (rho *  h.BOXSIZE^3)/Np

   h.npart[*]=0
   h.npart[0]=Np

   h.PARTTOTAL[*]=0
   h.PARTTOTAL[0]=Np
   
   write_head,fout,h
   add_block,fout,x,'POS '
   add_block,fout,v,'VEL '
   add_block,fout,id,'ID  '
   add_block,fout,m,'MASS'
   add_block,fout,u,'U   '

end