%N pgbeg %F $MIR/src/pgbeg.f
%D Open a graphics device
%B
      INTEGER FUNCTION PGBEG (UNIT, FILE, NXSUB, NYSUB)
      INTEGER       UNIT
      CHARACTER*(*) FILE
      INTEGER       NXSUB, NYSUB

 Note: new programs should use PGOPEN rather than PGBEG. PGOPEN
 is retained for compatibility with existing programs. Unlike PGOPEN,
 PGBEG closes any graphics devices that are already open, so it 
 cannot be used to open devices to be used in parallel.

 PGBEG opens a graphical device or file and prepares it for
 subsequent plotting. A device must be opened with PGBEG or PGOPEN
 before any other calls to PGPLOT subroutines for the device.

 If any device  is already open for PGPLOT output, it is closed before
 the new device is opened.

 Returns:
  PGBEG         : a status return value. A value of 1 indicates
                    successful completion, any other value indicates
                    an error. In the event of error a message is
                    written on the standard error unit.  
                    To test the return value, call
                    PGBEG as a function, eg IER=PGBEG(...); note
                    that PGBEG must be declared INTEGER in the
                    calling program. Some Fortran compilers allow
                    you to use CALL PGBEG(...) and discard the
                    return value, but this is not standard Fortran.
 Arguments:
  UNIT  (input)   : this argument is ignored by PGBEG (use zero).
  FILE  (input)   : the "device specification" for the plot device.
                    (For explanation, see description of PGOPEN.)
  NXSUB  (input)  : the number of subdivisions of the view surface in
                    X (>0 or <0).
  NYSUB  (input)  : the number of subdivisions of the view surface in
                    Y (>0).
                    PGPLOT puts NXSUB x NYSUB graphs on each plot
                    page or screen; when the view surface is sub-
                    divided in this way, PGPAGE moves to the next
                    panel, not the  next physical page. If
                    NXSUB > 0, PGPLOT uses the panels in row
                    order; if <0, PGPLOT uses them in column order.
