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MPI_Alltoallw(3) MPI MPI_Alltoallw(3)

NAME

MPI_Alltoallw - Generalized all-to-all communication allowing different datatypes, counts, and displacements for each partner

SYNOPSIS



int MPI_Alltoallw(const void *sendbuf, const int sendcounts[],
const int sdispls[], const MPI_Datatype sendtypes[],
void *recvbuf, const int recvcounts[], const int rdispls[],
const MPI_Datatype recvtypes[], MPI_Comm comm)




int MPI_Alltoallw_c(const void *sendbuf, const MPI_Count sendcounts[],
const MPI_Aint sdispls[], const MPI_Datatype sendtypes[],
void *recvbuf, const MPI_Count recvcounts[],
const MPI_Aint rdispls[], const MPI_Datatype recvtypes[],
MPI_Comm comm)










INPUT PARAMETERS



  

  
- starting address of send buffer (choice)

  

  
- non-negative integer array (of length group size) specifying the number
      of elements to send to each rank (non-negative integer)

  

  
- integer array (of length group size). Entry j specifies the displacement
      in bytes (relative to sendbuf) from which to take the outgoing data
      destined for process j (integer)

  

  
- array of datatypes (of length group size). Entry j specifies the type of
      data to send to process j (handle)

  

  
- non-negative integer array (of length group size) specifying the number
      of elements that can be received from each rank (non-negative
    integer)

  

  
- integer array (of length group size). Entry i specifies the displacement
      in bytes (relative to recvbuf) at which to place the incoming data from
      process i (integer)

  

  
- array of datatypes (of length group size). Entry i specifies the type of
      data received from process i (handle)

  

  
- communicator (handle)
    

  








OUTPUT PARAMETERS



  

  
- address of receive buffer (choice)
    

  








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








NOTES FOR FORTRAN


All MPI routines in Fortran (except for MPI_WTIME and
    MPI_WTICK ) have an additional argument ierr at the end of the
    argument list. 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 call statement.


All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are
    of type INTEGER in Fortran.








ERRORS


All MPI routines (except MPI_Wtime and 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 MPI_Comm_set_errhandler (for
    communicators), MPI_File_set_errhandler (for files), and
    MPI_Win_set_errhandler (for RMA windows). The MPI-1 routine
    MPI_Errhandler_set may be used but its use is deprecated. 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; however, MPI implementations will
    attempt to continue whenever possible.





  

  
- No error; MPI routine completed successfully.

  

  
- Invalid buffer pointer. Usually a null buffer where one is not
    valid.

  

  
- Invalid communicator. A common error is to use a null communicator in a
      call (not even allowed in MPI_Comm_rank ).

  

  
- Invalid count argument. Count arguments must be non-negative; a count of
      zero is often valid.

  

  
- Invalid datatype argument. Additionally, this error can occur if an
      uncommitted MPI_Datatype (see MPI_Type_commit ) is used in a
      communication call.

  

  
- Other error; use MPI_Error_string to get more information about
      this error code.
    

  









  

    2/9/2024