[97] | 1 | .\"Copyright 2006-2008 Sun Microsystems, Inc. |
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| 2 | .\" Copyright (c) 1996 Thinking Machines Corporation |
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| 3 | .TH MPI_Type_struct 3 "Dec 08, 2009" "1.4" "Open MPI" |
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| 4 | .SH NAME |
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| 5 | \fBMPI_Type_struct\fP \- Creates a \fIstruct\fP data type -- use of this routine is deprecated. |
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| 6 | |
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| 7 | .SH SYNTAX |
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| 8 | .ft R |
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| 9 | .SH C Syntax |
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| 10 | .nf |
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| 11 | #include <mpi.h> |
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| 12 | int MPI_Type_struct(int \fIcount\fP, int\fI *array_of_blocklengths\fP, |
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| 13 | MPI_Aint\fI *array_of_displacements\fP, MPI_Datatype\fI *array_of_types\fP, |
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| 14 | MPI_Datatype\fI *newtype\fP) |
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| 15 | |
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| 16 | .SH Fortran Syntax |
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| 17 | .nf |
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| 18 | INCLUDE 'mpif.h' |
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| 19 | MPI_TYPE_STRUCT(\fICOUNT, ARRAY_OF_BLOCKLENGTHS, |
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| 20 | ARRAY_OF_DISPLACEMENTS, ARRAY_OF_TYPES, |
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| 21 | NEWTYPE, IERROR\fP) |
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| 22 | INTEGER \fICOUNT, ARRAY_OF_BLOCKLENGTHS(*)\fP |
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| 23 | INTEGER \fIARRAY_OF_DISPLACEMENTS(*)\fP |
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| 24 | INTEGER \fIARRAY_OF_TYPES(*), NEWTYPE, IERROR\fP |
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| 25 | |
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| 26 | |
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| 27 | .SH INPUT PARAMETERS |
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| 28 | .ft R |
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| 29 | .TP 1i |
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| 30 | count |
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| 31 | Number of blocks (integer) also number of entries in arrays |
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| 32 | array_of_types, array_of_displacements, and array_of_blocklengths. |
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| 33 | .TP 1i |
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| 34 | array_of_blocklengths |
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| 35 | Number of elements in each block (array). |
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| 36 | .TP 1i |
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| 37 | array_of_displacements |
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| 38 | Byte displacement of each block (array). |
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| 39 | .TP 1i |
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| 40 | array_of_types |
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| 41 | Type of elements in each block (array of handles to datatype objects). |
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| 42 | .sp |
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| 43 | |
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| 44 | .SH OUTPUT PARAMETERS |
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| 45 | .ft R |
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| 46 | .TP 1i |
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| 47 | newtype |
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| 48 | New datatype (handle). |
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| 49 | .ft R |
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| 50 | .TP 1i |
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| 51 | IERROR |
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| 52 | Fortran only: Error status (integer). |
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| 53 | |
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| 54 | .SH DESCRIPTION |
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| 55 | .ft R |
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| 56 | Note that use of this routine is \fIdeprecated\fP as of MPI-2. Use MPI_Type_create_struct instead. |
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| 57 | .sp |
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| 58 | This deprecated routine is not available in C++. |
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| 59 | .sp |
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| 60 | MPI_Type_struct is the most general type constructor. It further generalizes MPI_Type_hindexed in that it allows each block to consist of replications of different datatypes. |
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| 61 | .sp |
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| 62 | \fBExample:\fP Let type1 have type map |
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| 63 | .nf |
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| 64 | |
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| 65 | {(double, 0), (char, 8)} |
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| 66 | |
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| 67 | .fi |
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| 68 | with extent 16. Let B = (2, 1, 3), D = (0, 16, 26), and T = (MPI_FLOAT, type1, MPI_CHAR). Then a call to MPI_Type_struct(3, B, D, T, newtype) returns a datatype with type map |
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| 69 | .nf |
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| 70 | |
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| 71 | {(float, 0), (float,4), (double, 16), (char, 24), |
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| 72 | (char, 26), (char, 27), (char, 28)} |
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| 73 | |
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| 74 | .fi |
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| 75 | That is, two copies of MPI_FLOAT starting at 0, followed by one copy of type1 starting at 16, followed by three copies of MPI_CHAR, starting at 26. (We assume that a float occupies 4 bytes.) |
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| 76 | .sp |
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| 77 | For more information, see section 3.12.1 of the MPI-1.1 Standard. |
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| 78 | |
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| 79 | .SH NOTES |
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| 80 | If an upperbound is set explicitly by using the MPI datatype MPI_UB, the corresponding index must be positive. |
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| 81 | .sp |
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| 82 | The MPI-1 Standard originally made vague statements about padding and alignment; this was intended to allow the simple definition of structures that could be sent with a count greater than one. For example, |
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| 83 | .nf |
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| 84 | struct {int a; char b;} foo; |
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| 85 | .fi |
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| 86 | may have |
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| 87 | .nf |
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| 88 | sizeof(foo) = sizeof(int) + sizeof(char); |
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| 89 | .fi |
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| 90 | defining the extent of a datatype as including an epsilon, which would have allowed an implementation to make the extent an MPI datatype for this structure equal to 2*sizeof(int). However, since different systems might define different paddings, a clarification to the standard made epsilon zero. Thus, if you define a structure datatype and wish to send or receive multiple items, you should explicitly include an MPI_UB entry as the last member of the structure. For example, the following code can be used for the structure foo: |
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| 91 | .nf |
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| 92 | |
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| 93 | blen[0] = 1; indices[0] = 0; oldtypes[0] = MPI_INT; |
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| 94 | blen[1] = 1; indices[1] = &foo.b - &foo; oldtypes[1] = MPI_CHAR; |
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| 95 | blen[2] = 1; indices[2] = sizeof(foo); oldtypes[2] = MPI_UB; |
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| 96 | MPI_Type_struct( 3, blen, indices, oldtypes, &newtype ); |
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| 97 | |
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| 98 | .fi |
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| 99 | |
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| 100 | .SH ERRORS |
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| 101 | Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument. C++ functions do not return errors. If the default error handler is set to MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism will be used to throw an MPI:Exception object. |
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| 102 | .sp |
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| 103 | Before the error value is returned, the current MPI error handler is |
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| 104 | called. By default, this error handler aborts the MPI job, except for I/O function errors. The error handler may be changed with MPI_Comm_set_errhandler; 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. |
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| 105 | |
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| 106 | .SH SEE ALSO |
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| 107 | .ft R |
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| 108 | .sp |
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| 109 | MPI_Type_create_struct |
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| 110 | .br |
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| 111 | MPI_Type_create_hindexed |
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| 112 | .br |
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| 113 | |
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