function td2ut, td
;
; Given a scalar or array of Dynamic Time Julian Day Numbers,
; return the corresponding Universal Time Julian Day Numbers.
;
; B. Knapp, 2002-12-18
;
; RCS Data:
;
; $Header$
;
; $Log$
;
; Print usage?
  n = n_elements( td )
  if n eq 0 then begin
     print, '     ut = td2ut( td )'
     return, ' '
  endif
;
; Use 32-bit or 64-bit shareable object library?
  mbits = ((!version.release ge 5.4) ? !version.memory_bits : 32)
  dll = getenv('bgkroot')+string(mbits,"('/lib/astron',i2,'.so')")
;
; Define output and then call the Fortran subroutine
  td_loc = double( td )
  ut = dblarr( n )
  result = call_external( dll, 'td2ut_arg_', n, td_loc, ut )
;
; Return scalar or array, according to argument td
  if (size( td ))[0] eq 0 then $
     return, ut[0] $
  else $
     return, ut
  end