MPI_Constants - Defines constants


STANDARDS

       This release implements the MPI 1.2 standard, as
       documented by the MPI Forum in the spring 1997 release of
       MPI:  A Message Passing Interface Standard.


DESCRIPTION

       The MPI_Constants routine defines constants of the
       following types:

       *   Communicators

       *   Groups

       *   Results of compare operations

       *   Collective operations

       *   Permanent key values

       *   Null objects

       *   Predefined constants

       *   Topology types

       *   MPI status

       *   Special MPI types and functions

   Communicators
       The following communicator constants are of type MPI_Comm
       in C and type integer in Fortran:

       MPI_COMM_WORLD      Specifies a constant that contains all
                           of the processes

       MPI_COMM_SELF       Specifies a constant that contains
                           only the calling process

   Groups
       The following group constant is of type MPI_Group in C and
       type integer in Fortran:

       MPI_GROUP_EMPTY     Specifies a group that contains no
                           members

   Compare Operation Results
       The following constants specify results of compare
       operations:

       MPI_IDENT           The groups are identical.

                           for MPI_Comm_compare(3)).

       MPI_SIMILAR         The groups contain the same members,
                           but in a different order.

       MPI_UNEQUAL         The groups are not equal.

   Collective Operations
       The collective combination operations (MPI_Reduce(3),
       MPI_Allreduce(3), MPI_Reduce_scatter(3), and MPI_Scan(3))
       take a combination operation.  This combination operation
       is of type MPI_Op in C and of type integer in Fortran.
       The predefined operations are as follows:

       MPI_MAX             Returns the maximum value

       MPI_MIN             Returns the minumum value

       MPI_SUM             Returns the sum

       MPI_PROD            Returns the product

       MPI_LAND            Returns the logical AND

       MPI_BAND            Returns the bitwise AND

       MPI_LOR             Returns the logical OR

       MPI_BOR             Returns the bitwise OR

       MPI_LXOR            Returns the logical exclusive OR

       MPI_BXOR            Returns the bitwise exclusive OR

       MPI_MINLOC          Returns the minimum value and the
                           location (actually, it returns the
                           value of the second element of the
                           structure where the minimum of the
                           first element is found)

       MPI_MAXLOC          Returns the maximum value and the
                           location

   Permanent Key Values
       The types of the following permanent key value constants
       are the same in C and Fortran:

       MPI_TAG_UB               Specifies largest tag value

       MPI_HOST                 Specifies the rank of the process
                                that is host, if any

       MPI_IO                   Specifies the rank of the process


       MPI_WTIME_IS_GLOBAL      Has a value of 1 if MPI_Wtime(3)
                                is globally synchronized

   Null Objects
       The following constants specify null objects:

       MPI_COMM_NULL            Specifies a null communicator

       MPI_OP_NULL              Specifies a null operation

       MPI_GROUP_NULL           Specifies a null group

       MPI_DATATYPE_NULL        Specifies a null data type

       MPI_REQUEST_NULL         Specifies a null request

       MPI_ERRHANDLER_NULL      Specifies a null error handler

   Predefined Constants
       The following constants are predefined:

       MPI_MAX_PROCESSOR_NAME        Specifies the maximum length
                                     of the name returned by
                                     MPI_Get_processor_name(3)

       MPI_MAX_ERROR_STRING          Specifies the maximum length
                                     of the string returned by
                                     MPI_Error_string(3)

       MPI_UNDEFINED                 Used by many routines to
                                     indicate an undefined or
                                     unknown integer value

       MPI_UNDEFINED_RANK            Specifies an unknown rank

       MPI_KEYVAL_INVALID            Provides a special key value
                                     that can be used to detect
                                     uninitialized key values

       MPI_BSEND_OVERHEAD            Specifies a value that can
                                     be added to the size of a
                                     MPI_Bsend(3) buffer for each
                                     outstanding message

       MPI_PROC_NULL                 Specifies a rank that can be
                                     used to send or receive from
                                     no-one

       MPI_ANY_SOURCE                Indicates, in a receive, to
                                     accept a message from anyone

       MPI_ANY_TAG                   Indicates, in a receive, to

                                     tag value

       MPI_BOTTOM                    Can be used to indicate the
                                     bottom of the address space

   Topology Types
       The following constants are topology types:

       MPI_GRAPH      Indicates a general graph

       MPI_CART       Indicates a Cartesian grid

   MPI Status
       The MPI_Status data type is a structure.  The elements
       that programmers can use are as follows:

       MPI_SOURCE     Indicates who sent the message

       MPI_TAG        Indicates with what tag the message was
                      sent

       MPI_ERROR      Indicates any error return

   Special MPI Types and Functions
       The following constants are special MPI types and
       functions:

       MPI_Aint                      Specifies a C type that
                                     holds any valid address

       MPI_Handler_function          Specifies a C function for
                                     handling errors (see the
                                     MPI_Errhandler_create(3) man
                                     page)

       MPI_User_function             Specifies a C function to
                                     combine values (see the
                                     Collective Operations
                                     subsection on this man page)
                                     and the MPI_Op_create(3) man
                                     page)

       MPI_Copy_function             Specifies a function to copy
                                     attributes (see the
                                     MPI_Keyval_create(3) man
                                     page)

       MPI_Delete_function           Specifies a function to
                                     delete attributes (see the
                                     MPI_Keyval_create(3) man
                                     page)

       MPI_ERRORS_ARE_FATAL          Specifies an error handler


       MPI_ERRORS_RETURN             Specifies an error handler
                                     that returns error codes (as
                                     a value of the MPI routine
                                     in C and through the last
                                     argument in Fortran)


SEE ALSO

       MPI_Allreduce(3), MPI_Bsend(3), MPI_Comm_compare(3),
       MPI_Errhandler_create(3), MPI_Error_string(3),
       MPI_Get_processor_name(3), MPI_Keyval_create(3),
       MPI_Op_create(3), MPI_Reduce(3), MPI_Reduce_scatter(3),
       MPI_Scan(3), MPI_Wtime(3)


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