NAME

       pvm_siblings  -   return the number and associated task ids of processes that were started
       together in a single spawn call.

SYNOPSIS

       C    int ntids = pvm_siblings( int **tids )

       Fortran   call pvmfsiblings( ntids, index, sibling )

PARAMETERS

       ntids   Returns the number of tids that were spawned together. Value less than 0 indicates
               an error.

       tids    Pointer  to the array of tids that contains the siblings. Indexed from 0 to (ntids
               - 1)

       index   Integer index of tid to be returned in sibling.  If  index  is  set  to  -1,  then
               sibling is unchanged. Otherwise, must be in the range [0, ntids - 1]

       sibling When  index  is  in  the range [0, ntids -1], this contains the tid of the desired
               index.

DESCRIPTION

       The routine pvm_siblings returns the number of tasks and a list of task ids  of  processes
       that  were  spawned together in a single spawn call. The spawning task multicasts the list
       of successful to the spawned tasks so that each task has an identical copy of the  sibling
       list.   pvm_siblings  uses local storage to keep the list of tids and does not update this
       list when sibling tasks exit the virtual machine.   The  FORTRAN  version  allows  calling
       programs  read  a  particular  index  in  the  internal sibling array.  If pvm_siblings is
       successful, ntids will be  > 0. If some error occurs then ntids will be < 0.

       pvm_siblings is designed to simplify the logic in static spmd-style  programs.  By  giving
       tasks an identical list of tids and its size, programs may self size and treat the sibling
       as static map between instances and tasks. The internal list is not updated  when  sibling
       tasks exit the virtual machine and should be treated as a snapshot of the parallel program
       when it was first started.

       If a task was started by pvm_spawn, then pvm_siblings will return ntids = 1 and

       ntids = 1 and tids will contain a single entry  identical  to  the  task  id  returned  by
       pvm_mytid()

EXAMPLES

       C:
            int *tids;
            ntids = pvm_siblings(&tids);

       Fortran:
            INTEGER TIDS(0:MAXNPROC)
            CALL PVMFSIBLINGS(NTIDS, -1, IDUM)
            DO I = 0, NTIDS-1
               CALL PVMFSIBLINGS(NTIDS, I, TIDS(I))

ERRORS

       pvm_siblings can return the following error codes

       PvmNoTask
              No task at that index, or index is invalid.

SEE ALSO

       pvm_spawn(3PVM), pvm_mytid(3PVM), pvm_parent(3PVM)

                                          26 June, 1997                            SIBLINGS(3PVM)