BCAST(3PVM)

NAME
pvm_bcast - Broadcasts the data in the active message buffer to a group of processes.

SYNOPSIS
C    int info = pvm_bcast( char *group, int msgtag )
Fortran    call pvmfbcast( group, msgtag, info )

PARAMETERS

group
    Character string group name of an existing group.

msgtag
    Integer message tag supplied by the user. msgtag should be >= 0. It allows the user's program to distinguish between different kinds of messages .
    info integer status code returned by the routine. Values less than zero indicate an error.

DISCUSSION
The routine pvm_bcast broadcasts a message stored in the active send buffer to all the members of group. In PVM 3.2 the broadcast message is not sent back to the sender. Any PVM task can call pvm_bcast(), it need not be a member of the group. The content of the message can be distinguished by msgtag. If pvm_bcast is successful, info will be 0. If some error occurs then info will be < 0.

pvm_bcast is asynchronous. Computation on the sending processor resumes as soon as the message is safely on its way to the receiving processors. This is in contrast to synchronous communication, during which computation on the sending processor halts until a matching receive is executed by all the receiving processors.

pvm_bcast first determines the tids of the group members by checking a group data base. A multicast is performed to these tids. If the group is changed during a broadcast the change will not be reflected in the broadcast. Multicasting is not supported by most multiprocessor vendors. Typically their native calls only support broadcasting to all the user's processes on a multiprocessor. Because of this omission, pvm_bcast may not be an efficient communication method on some multiprocessors.

EXAMPLES
C:
	info = pvm_initsend( PvmDataRaw );
	info = pvm_pkint( array, 10, 1 );
	msgtag = 5 ;
	info = pvm_bcast( "worker", msgtag );

Fortran:
	CALL PVMFINITSEND( PVMDEFAULT )
	CALL PVMFPKFLOAT( DATA, 100, 1, INFO )
	CALL PVMFBCAST( 'worker', 5, INFO )

ERRORS
These error conditions can be returned by pvm_bcast
	PvmSysErr	pvmd was not started or has crashed.
	PvmBadParam	giving a negative msgtag.
	PvmNoGroup	giving a non-existent group name.

SEE ALSO
joingroup(3PVM)