* data: density, pressure, and three momenta for t=65 Myr
  of model Hc1b13a of Heitsch & Putman 2009.
* reading statement (e.g. into IDL):

  ndim  = 0l ; number of dimensions
  incbdy= 0l ; including boundary layers? 
  nx    = 0l ; dimensions
  nxtot = 0l ; +boundary layers
  ixbeg = 0l ; first active zone
  ixend = 0l ; last active zone
  ny    = 0l ; ... etc
  nytot = 0l
  iybeg = 0l
  iyend = 0l
  nz    = 0l
  nztot = 0l
  izbeg = 0l
  izend = 0l
  dmp   = 0l   ; dump number
  timec = 0.0  ; code time
  iter  = 0l   ; iteration
  openr,dun,"dens0032.f7u",/get_lun,/f77
  readu,dun,ndim,incbdy
  readu,dun,nx,nxtot,ixbeg,ixend
  readu,dun,ny,nytot,iybeg,iyend
  readu,dun,nz,nztot,izbeg,izend
  readu,dun,dmp,timec,iter
  cube = fltarr(nx,ny,nz)
  readu,dun,cube
  free_lun,dun

* box length (in code units): 2.81e-2x2.81e-2x1.124e-1
             (in cells)     : 128x128x512
* units (read as "multiply by factor to convert from code to physical units"):
  density   : 1.0e-2   [cm^(-3)]
  pressure  : 1.0e2    [K cm^(-3)]
  velocity  : 9.118    [km s^(-1)]
  time      : 9.528e2  [Myr]
  length    : 8.896e3  [pc]

* The code time counter is in the variable timec.