pvm_nrecv - Non-blocking receive.

       The routine pvm_nrecv checks to see if a message with label msgtag has arrived from tid.  and also clears
       the current receive buffer if any, If a matching message has arrived  pvm_nrecv  immediately  places  the
       message in a new active receive buffer, and returns the buffer identifier in bufid.

       If  the requested message has not arrived, then pvm_nrecv immediately returns with a 0 in bufid.  If some
       error occurs bufid will be < 0.

       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_nrecv will accept a message from any process which has a matching
       msgtag.   If  msgtag  = -1 and tid is defined by the user, then pvm_nrecv will accept any message that is
       sent from process tid.  If tid = -1 and msgtag = -1, then pvm_nrecv 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.

       pvm_nrecv  is  non-blocking  in  the  sense  that  the routine always returns immediately either with the
       message or with the information that the message has not arrived at the local pvmd yet.  pvm_nrecv can be
       called multiple times to check if a given message has arrived yet.   In  addition  the  blocking  receive
       pvm_recv  can  be  called for the same message if the application runs out of work it could do before the
       data arrives.

       If pvm_nrecv returns with the message, then the data in the message  can  be  unpacked  into  the  user's
       memory using the unpack routines.

       These error conditions can be returned by pvm_nrecv.

       PvmBadParam
              giving an invalid tid value or msgtag.

       PvmSysErr
              pvmd not responding.

       C:
            tid = pvm_parent();
            msgtag = 4 ;
            arrived = pvm_nrecv( tid, msgtag );
            if ( arrived > 0)
                 info = pvm_upkint( tid_array, 10, 1 );
            else
                 /* go do other computing */

       Fortran:
            CALL PVMFNRECV( -1, 4, ARRIVED )
            IF ( ARRIVED .gt. 0 ) THEN
               CALL PVMFUNPACK( INTEGER4, TIDS, 25, 1, INFO )
               CALL PVMFUNPACK( REAL8, MATRIX, 100, 100, INFO )
            ELSE
       *       GO DO USEFUL WORK
            ENDIF

       pvm_nrecv - Non-blocking receive.

       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  returning  the value of the new active receive buffer identifier.  Values less than zero
               indicate an error.

pvm_bufinfo(3PVM), pvm_getminfo(3PVM), pvm_recv(3PVM), pvm_unpack(3PVM), pvm_send(3PVM), pvm_mcast(3PVM)

                                                 30 August, 1993                                     NRECV(3PVM)

Cintbufid=pvm_nrecv(inttid,intmsgtag)Fortrancallpvmfnrecv(tid,msgtag,bufid)