.TH MPI_Irsend 3 "11/12/2019" " " "MPI"

.SH NAME

MPI_Irsend \-  Starts a nonblocking ready send 

.SH SYNOPSIS

.nf

int MPI_Irsend(const void *buf, int count, MPI_Datatype datatype, int dest, int tag,

MPI_Comm comm, MPI_Request * request)

.fi

.SH INPUT PARAMETERS

.PD 0

.TP

.B buf 

- initial address of send buffer (choice)

.PD 1

.PD 0

.TP

.B count 

- number of elements in send buffer (integer)

.PD 1

.PD 0

.TP

.B datatype 

- datatype of each send buffer element (handle)

.PD 1

.PD 0

.TP

.B dest 

- rank of destination (integer)

.PD 1

.PD 0

.TP

.B tag 

- message tag (integer)

.PD 1

.PD 0

.TP

.B comm 

- communicator (handle)

.PD 1

.SH OUTPUT PARAMETERS

.PD 0

.TP

.B request 

- communication request (handle)

.PD 1

.SH THREAD AND INTERRUPT SAFETY

This routine is thread-safe.  This means that this routine may be

safely used by multiple threads without the need for any user-provided

thread locks.  However, the routine is not interrupt safe.  Typically,

this is due to the use of memory allocation routines such as 

.I malloc

or other non-MPICH runtime routines that are themselves not interrupt-safe.

.SH NOTES FOR FORTRAN

All MPI routines in Fortran (except for 

.I MPI_WTIME

and 

.I MPI_WTICK

) have

an additional argument 

.I ierr

at the end of the argument list.  

.I ierr

is an integer and has the same meaning as the return value of the routine

in C.  In Fortran, MPI routines are subroutines, and are invoked with the

.I call

statement.

All MPI objects (e.g., 

.I MPI_Datatype

, 

.I MPI_Comm

) are of type 

.I INTEGER

in Fortran.

.SH ERRORS

All MPI routines (except 

.I MPI_Wtime

and 

.I MPI_Wtick

) return an error value;

C routines as the value of the function and Fortran routines in the last

argument.  Before the value is returned, the current MPI error handler is

called.  By default, this error handler aborts the MPI job.  The error handler

may be changed with 

.I MPI_Comm_set_errhandler

(for communicators),

.I MPI_File_set_errhandler

(for files), and 

.I MPI_Win_set_errhandler

(for

RMA windows).  The MPI-1 routine 

.I MPI_Errhandler_set

may be used but

its use is deprecated.  The predefined error handler

.I MPI_ERRORS_RETURN

may be used to cause error values to be returned.

Note that MPI does 

.B not

guarentee that an MPI program can continue past

an error; however, MPI implementations will attempt to continue whenever

possible.

.PD 0

.TP

.B MPI_SUCCESS 

- No error; MPI routine completed successfully.

.PD 1

.PD 0

.TP

.B MPI_ERR_COMM 

- Invalid communicator.  A common error is to use a null

communicator in a call (not even allowed in 

.I MPI_Comm_rank

).

.PD 1

.PD 0

.TP

.B MPI_ERR_COUNT 

- Invalid count argument.  Count arguments must be 

non-negative; a count of zero is often valid.

.PD 1

.PD 0

.TP

.B MPI_ERR_TYPE 

- Invalid datatype argument.  Additionally, this error can

occur if an uncommitted MPI_Datatype (see 

.I MPI_Type_commit

) is used

in a communication call.

.PD 1

.PD 0

.TP

.B MPI_ERR_TAG 

- Invalid tag argument.  Tags must be non-negative; tags

in a receive (

.I MPI_Recv

, 

.I MPI_Irecv

, 

.I MPI_Sendrecv

, etc.) may

also be 

.I MPI_ANY_TAG

\&.

The largest tag value is available through the 

the attribute 

.I MPI_TAG_UB

\&.

.PD 1

.PD 0

.TP

.B MPI_ERR_RANK 

- Invalid source or destination rank.  Ranks must be between

zero and the size of the communicator minus one; ranks in a receive

(

.I MPI_Recv

, 

.I MPI_Irecv

, 

.I MPI_Sendrecv

, etc.) may also be 

.I MPI_ANY_SOURCE

\&.

.PD 1

.PD 0

.TP

.B MPI_ERR_INTERN 

- This error is returned when some part of the MPICH 

implementation is unable to acquire memory.  

.PD 1