1MPI_Op_create(3) LAM/MPI MPI_Op_create(3)
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6 MPI_Op_create - Creates a user-defined combination function handle
7
9 #include <mpi.h>
10 int MPI_Op_create(MPI_User_function func, int commute,
11 MPI_Op *pop)
12
14 func - user defined function (function)
15 commute
16 - true if commutative; false otherwise.
17
20 pop - operation (handle)
21
24 The calling list for the user function type is
25 typedef void (MPI_User_function) ( void * a,
27 void * b, int * len, MPI_Datatype * );
28 where the operation is b[i] = a[i] op b[i] , for i = 0, ... , len-1 .
31 A pointer to the datatype given to the MPI collective computation rou‐
32 tine (i.e., MPI_Reduce , MPI_Allreduce , MPI_Scan , or MPI_Reduce_scat‐
33 ter ) is also passed to the user-specified routine.
34
37 When the MPI_Op created by this function is no longer being used, it
38 should be freed with MPI_Op_free .
39
43 All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK ) have
44 an additional argument ierr at the end of the argument list. ierr is
45 an integer and has the same meaning as the return value of the routine
46 in C. In Fortran, MPI routines are subroutines, and are invoked with
47 the call statement.
48 All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are of type INTEGER in
50 Fortran.
51
54 The reduction functions ( MPI_Op ) do not return an error value. As a
55 result, if the functions detect an error, all they can do is either
56 call MPI_Abort or silently skip the problem. Thus, if you change the
57 error handler from MPI_ERRORS_ARE_FATAL to something else (e.g.,
58 MPI_ERRORS_RETURN ), then no error may be indicated.
59 The reason for this is the performance problems that arise in ensuring
61 that all collective routines return the same error value.
62
65 If an error occurs in an MPI function, the current MPI error handler is
66 called to handle it. By default, this error handler aborts the MPI
67 job. The error handler may be changed with MPI_Errhandler_set ; the
68 predefined error handler MPI_ERRORS_RETURN may be used to cause error
69 values to be returned (in C and Fortran; this error handler is less
70 useful in with the C++ MPI bindings. The predefined error handler
71 MPI::ERRORS_THROW_EXCEPTIONS should be used in C++ if the error value
72 needs to be recovered). Note that MPI does not guarantee that an MPI
73 program can continue past an error.
74 All MPI routines (except MPI_Wtime and MPI_Wtick ) return an error
76 value; C routines as the value of the function and Fortran routines in
77 the last argument. The C++ bindings for MPI do not return error val‐
78 ues; instead, error values are communicated by throwing exceptions of
79 type MPI::Exception (but not by default). Exceptions are only thrown
80 if the error value is not MPI::SUCCESS .
81 Note that if the MPI::ERRORS_RETURN handler is set in C++, while MPI
84 functions will return upon an error, there will be no way to recover
85 what the actual error value was.
86 MPI_SUCCESS
87 - No error; MPI routine completed successfully.
88 MPI_ERR_OP
89 - Invalid operation. MPI operations (objects of type MPI_Op )
90 must either be one of the predefined operations (e.g., MPI_SUM )
91 or created with MPI_Op_create . Additionally, only certain
92 datatypes are alloed with given predefined operations. See
93 MPI-1, section 4.9.2.
94 MPI_ERR_ARG
95 - Invalid argument. Some argument is invalid and is not identi‐
96 fied by a specific error class. This is typically a NULL
97 pointer or other such error.
98 MPI_ERR_OTHER
99 - This error is returned when some part of the LAM/MPI implemen‐
100 tation is unable to acquire memory.
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104 MPI_Op_free
105
108 For more information, please see the official MPI Forum web site, which
109 contains the text of both the MPI-1 and MPI-2 standards. These docu‐
110 ments contain detailed information about each MPI function (most of
111 which is not duplicated in these man pages).
112 http://www.mpi-forum.org/
114
118 The LAM Team would like the thank the MPICH Team for the handy program
119 to generate man pages ("doctext" from ftp://ftp.mcs.anl.gov/pub/sow‐
120 ing/sowing.tar.gz ), the initial formatting, and some initial text for
121 most of the MPI-1 man pages.
122
124 opcreate.c
125LAM/MPI 7.1.2 2/23/2006 MPI_Op_create(3)