Creates a persistent communication request for a receive operation. The argument \fIbuf\fP is marked as OUT because the user gives permission to write on the receive buffer by passing the argument to MPI_Recv_init.
.sp
A persistent communication request is inactive after it is created -- no active communication is attached to the request.
.sp
A communication (send or receive) that uses a persistent request is initiated by the function MPI_Start or MPI_Startall.
Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument. C++ functions do not return errors. If the default error handler is set to MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism will be used to throw an MPI::Exception object.
Before the error value is returned, the current MPI error handler is
called. By default, this error handler aborts the MPI job, except for I/O function errors. The error handler may be changed with MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.
