Constants

Meaning of MPIs defined constants

Data types

Note that the Fortran types should only be used in Fortran programs, and the C types should only be used in C programs. For example, it is in error to use MPI_INT for a Fortran INTEGER. Datatypes are of type MPI_Datatype in C and of tyep INTEGER in Fortran.

C datatypes

MPI_CHAR

char

MPI_BYTE

See standard; like unsigned char

MPI_SHORT

short

MPI_INT

int

MPI_LONG

long

MPI_FLOAT

float

MPI_DOUBLE

double

MPI_UNSIGNED_CHAR

unsigned char

MPI_UNSIGNED_SHORT

unsigned short

MPI_UNSIGNED

unsigned int

MPI_UNSIGNED_LONG

unsigned long

MPI_LONG_DOUBLE

long double (some systems may not implement)

The following are datatypes for the MPI functions MPI_MAXLOC and MPI_MINLOC.

MPI_FLOAT_INT

struct { float, int }

MPI_LONG_INT

struct { long, int }

MPI_DOUBLE_INT

struct { double, int }

MPI_SHORT_INT

struct { short, int }

MPI_2INT

struct { int, int }

MPI_LONG_DOUBLE_INT

struct { long double, int }; this is an OPTIONAL type, and may be set to NULL

MPI_LONG_LONG_INT

struct { long long, int }; this is an OPTIONAL type, and may be set to NULL.

Special datatypes for C and Fortran

MPI_PACKED

For MPI_Pack and MPI_Unpack

MPI_UB

For MPI_Type_struct; an upper-bound indicator

MPI_LB

For MPI_Type_struct; a lower-bound indicator

Fortran datatypes

MPI_REAL

REAL

MPI_INTEGER

INTEGER

MPI_LOGICAL

LOGICAL

MPI_DOUBLE_PRECISION

DOUBLE PRECISION

MPI_COMPLEX

COMPLEX

MPI_DOUBLE_COMPLEX

complex*16 (or complex*32) where supported.

The following datatypes are optional

MPI_INTEGER1

integer*1 if supported

MPI_INTEGER2

integer*2 if supported

MPI_INTEGER4

integer*4 if supported

MPI_REAL4

real*4 if supported

MPI_REAL8

real*8 if supported

The following are datatypes for the MPI functions MPI_MAXLOC and MPI_MINLOC. In Fortran, these datatype always consist of two elements of the same Fortran type.

MPI_2INTEGER

INTEGER,INTEGER

MPI_2REAL

REAL, REAL

MPI_2DOUBLE_PRECISION

DOUBLE PRECISION, DOUBLE PRECISION

MPI_2COMPLEX

COMPLEX, COMPLEX

MPI_2DOUBLE_COMPLEX

complex*16, complex*16

Communicators

Communicators are of type MPI_Comm in C and INTEGER in Fortran

MPI_COMM_WORLD

Contains all of the processes

MPI_COMM_SELF

Contains only the calling process

Groups

Groups are of type MPI_Group in C and INTEGER in Fortran

MPI_GROUP_EMPTY

A group containing no members.

Results of the compare operations

MPI_IDENT

Identical

MPI_CONGRUENT

(only for MPI_COMM_COMPARE) The groups are identical

MPI_SIMILAR

Same members, but in a different order

MPI_UNEQUAL

Different

Collective operations

The collective combination operations (MPI_REDUCE, MPI_ALLREDUCE, MPI_REDUCE_SCATTER, and MPI_SCAN) take a combination operation. This operation is of type MPI_Op in C and of type INTEGER in Fortran. The predefined operations are

MPI_MAX

return the maximum

MPI_MIN

return the minumum

MPI_SUM

return the sum

MPI_PROD

return the product

MPI_LAND

return the logical and

MPI_BAND

return the bitwise and

MPI_LOR

return the logical or

MPI_BOR

return the bitwise of

MPI_LXOR

return the logical exclusive or

MPI_BXOR

return the bitwise exclusive or

MPI_MINLOC

return the minimum and the location (actually, the value of the second element of the structure where the minimum of the first is found)

MPI_MAXLOC

return the maximum and the location

Notes on collective operations

The reduction functions (MPI_Op) do not return an error value. As a result, if the functions detect an error, all they can do is either call MPI_Abort or silently skip the problem. Thus, if you change the error handler from MPI_ERRORS_ARE_FATAL to something else, for example, MPI_ERRORS_RETURN, then no error may be indicated.

The reason for this is the performance problems in ensuring that all collective routines return the same error value.

Note that not all datatypes are valid for these functions. For example, MPI_COMPLEX is not valid for MPI_MAX and MPI_MIN. In addition, the MPI 1.1 standard did not include the C types MPI_CHAR and MPI_UNSIGNED_CHAR among the lists of arithmetic types for operations like MPI_SUM. However, since the C type char is an integer type (like short), it should have been included. The MPI Forum will probably include char and unsigned char as a clarification to MPI 1.1; until then, users are advised that MPI implementations may not accept MPI_CHAR and MPI_UNSIGNED_CHAR as valid datatypes for MPI_SUM, MPI_PROD, etc. MPICH does allow these datatypes.

Permanent key values

These are the same in C and Fortran

MPI_TAG_UB

Largest tag value

MPI_HOST

Rank of process that is host, if any

MPI_IO

Rank of process that can do I/O

MPI_WTIME_IS_GLOBAL

Has value 1 if MPI_WTIME is globally synchronized.

Null objects

MPI_COMM_NULL

Null communicator

MPI_OP_NULL

Null operation

MPI_GROUP_NULL

Null group

MPI_DATATYPE_NULL

Null datatype

MPI_REQUEST_NULL

Null request

MPI_ERRHANDLER_NULL

Null error handler

Predefined Constants

MPI_MAX_PROCESSOR_NAME

Maximum length of name returned by MPI_GET_PROCESSOR_NAME

MPI_MAX_ERROR_STRING

Maximum length of string return by MPI_ERROR_STRING

MPI_UNDEFINED

Used by many routines to indicated undefined or unknown integer value

MPI_UNDEFINED_RANK

Unknown rank

MPI_KEYVAL_INVALID

Special keyval that may be used to detect uninitialized keyvals.

MPI_BSEND_OVERHEAD

Add this to the size of a MPI_BSEND buffer for each outstanding message

MPI_PROC_NULL

This rank may be used to send or receive from no-one.

MPI_ANY_SOURCE

In a receive, accept a message from anyone.

MPI_ANY_TAG

In a receive, accept a message with any tag value.

MPI_BOTTOM

May be used to indicate the bottom of the address space

Topology types

MPI_GRAPH

General graph

MPI_CART

Cartesian grid

MPI Status

The MPI_Status datatype is a structure. The three elements for use by programmers are

MPI_SOURCE

Who sent the message

MPI_TAG

What tag the message was sent with

MPI_ERROR

Any error return

Special MPI types and functions

MPI_Aint

C type that holds any valid address.

MPI_Handler_function

C function for handling errors (see MPI_Errhandler_create) .

MPI_User_function

C function to combine values (see collective operations and MPI_Op_create)

MPI_Copy_function

Function to copy attributes (see MPI_Keyval_create)

MPI_NULL_COPY_FN

Predefined copy function

MPI_Delete_function

Function to delete attributes (see MPI_Keyval_create)

MPI_NULL_DELETE_FN

Predefined delete function

MPI_DUP_FN

Predefined duplication function

MPI_ERRORS_ARE_FATAL

Error handler that forces exit on error

MPI_ERRORS_RETURN

Error handler that returns error codes (as value of MPI routine in C and through last argument in Fortran)

MPI Error classes

MPI_SUCCESS

Successful return code

MPI_ERR_BUFFER

Invalid buffer pointer

MPI_ERR_COUNT

Invalid count argument

MPI_ERR_TYPE

Invalid datatype argument

MPI_ERR_TAG

Invalid tag argument

MPI_ERR_COMM

Invalid communicator

MPI_ERR_RANK

Invalid rank

MPI_ERR_ROOT

Invalid root

MPI_ERR_GROUP

Null group passed to function

MPI_ERR_OP

Invalid operation

MPI_ERR_TOPOLOGY

Invalid topology

MPI_ERR_DIMS

Illegal dimension argument

MPI_ERR_ARG

Invalid argument

MPI_ERR_UNKNOWN

Unknown error

MPI_ERR_TRUNCATE

message truncated on receive

MPI_ERR_OTHER

Other error; use Error_string

MPI_ERR_INTERN

internal error code

MPI_ERR_IN_STATUS

Look in status for error value

MPI_ERR_PENDING

Pending request

MPI_ERR_REQUEST

illegal mpi_request handle

MPI_ERR_LASTCODE

Last error code -- always at end

Location:/home/MPI/mansrc/mpiconsts.txt