RECV(3PVM)							   RECV(3PVM)

NAME
  pvm_recv - Receive a message.

SYNOPSIS
  C	  int bufid = pvm_recv(	int tid, int msgtag )

  Fortran call pvmfrecv( tid, msgtag, bufid )

PARAMETERS

  tid	  Integer task identifier of sending process supplied by the user.

  msgtag  Integer message tag supplied by the user.  msgtag should be >= 0.

  bufid	  Integer returns the value of the new active receive buffer identif-
	  ier.	Values less than zero indicate an error.

DISCUSSION
  The routine pvm_recv blocks the process until	a message with label msgtag
  has arrived from tid.	pvm_recv then places the message in a new active
  receive buffer, which	also clears the	current	receive	buffer.

  A -1 in msgtag or tid	matches	anything.  This	allows the user	the following
  options.  If tid = -1	and msgtag is defined by the user, then	pvm_recv will
  accept a message from	any process which has a	matching msgtag.  If msgtag =
  -1 and tid is	defined	by the user, then pvm_recv will	accept any message
  that is sent from process tid.  If tid = -1 and msgtag = -1, then pvm_recv
  will accept any message from any process.

  The PVM model	guarantees the following about message order.  If task 1
  sends	message	A to task 2, then task 1 sends message B to task 2, message A
  will arrive at task 2	before message B.  Moreover, if	both messages arrive
  before task 2	does a receive,	then a wildcard	receive	will always return
  message A.

  If pvm_recv is successful, bufid will	be the value of	the new	active
  receive buffer identifier.  If some error occurs then	bufid will be <	0.

  pvm_recv is blocking which means the routine waits until a message matching
  the user specified tid and msgtag values arrives at the local	pvmd. If the
  message has already arrived then pvm_recv returns immediately	with the mes-
  sage.

  Once pvm_recv	returns, the data in the message can be	unpacked into the
  user's memory	using the unpack routines.

EXAMPLES
  C:
	  tid =	pvm_parent();
	  msgtag = 4 ;
	  bufid	= pvm_recv( tid, msgtag	);
	  info = pvm_upkint( tid_array,	10, 1 );
	  info = pvm_upkint( problem_size, 1, 1	);
	  info = pvm_upkfloat( input_array, 100, 1 );

  Fortran:
	  CALL PVMFRECV( -1, 4,	BUFID )
	  CALL PVMFUNPACK( INTEGER4, TIDS, 25, 1, INFO )
	  CALL PVMFUNPACK( REAL8, MATRIX, 100, 100, INFO )

ERRORS
  These	error conditions can be	returned by pvm_recv
       PvmBadParam    giving an	invalid	tid value, or msgtag < -1.
       PvmSysErr      pvmd not responding.

SEE ALSO
  pvm_nrecv(3PVM), pvm_unpack(3PVM), pvm_probe(3PVM), pvm_send(3PVM),
  pvm_mcast(3PVM)