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ScaLAPACK
2.0.2
ScaLAPACK: Scalable Linear Algebra PACKage
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ScaLAPACK
2.0.2
ScaLAPACK: Scalable Linear Algebra PACKage
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#include "../pblas.h"#include "../PBpblas.h"#include "../PBtools.h"#include "../PBblacs.h"#include "../PBblas.h"Go to the source code of this file.
Functions/Subroutines | |
| void | PB_Cdescset (int *DESC, int M, int N, int IMB, int INB, int MB, int NB, int RSRC, int CSRC, int CTXT, int LLD) |
| void PB_Cdescset | ( | int * | DESC, |
| int | M, | ||
| int | N, | ||
| int | IMB, | ||
| int | INB, | ||
| int | MB, | ||
| int | NB, | ||
| int | RSRC, | ||
| int | CSRC, | ||
| int | CTXT, | ||
| int | LLD | ||
| ) |
Definition at line 23 of file PB_Cdescset.c.
{
/*
* Purpose
* =======
*
* PB_Cdescset uses its 10 input arguments M, N, IMB, INB, MB, NB,
* RSRC, CSRC, CTXT and LLD to initialize a descriptor vector of type
* BLOCK_CYCLIC_2D_INB.
*
* Notes
* =====
*
* A description vector is associated with each 2D block-cyclicly dis-
* tributed matrix. This vector stores the information required to
* establish the mapping between a matrix entry and its corresponding
* process and memory location.
*
* In the following comments, the character _ should be read as
* "of the distributed matrix". Let A be a generic term for any 2D
* block cyclicly distributed matrix. Its description vector is DESC_A:
*
* NOTATION STORED IN EXPLANATION
* ---------------- --------------- ------------------------------------
* DTYPE_A (global) DESCA[ DTYPE_ ] The descriptor type.
* CTXT_A (global) DESCA[ CTXT_ ] The BLACS context handle, indicating
* the NPROW x NPCOL BLACS process grid
* A is distributed over. The context
* itself is global, but the handle
* (the integer value) may vary.
* M_A (global) DESCA[ M_ ] The number of rows in the distribu-
* ted matrix A, M_A >= 0.
* N_A (global) DESCA[ N_ ] The number of columns in the distri-
* buted matrix A, N_A >= 0.
* IMB_A (global) DESCA[ IMB_ ] The number of rows of the upper left
* block of the matrix A, IMB_A > 0.
* INB_A (global) DESCA[ INB_ ] The number of columns of the upper
* left block of the matrix A,
* INB_A > 0.
* MB_A (global) DESCA[ MB_ ] The blocking factor used to distri-
* bute the last M_A-IMB_A rows of A,
* MB_A > 0.
* NB_A (global) DESCA[ NB_ ] The blocking factor used to distri-
* bute the last N_A-INB_A columns of
* A, NB_A > 0.
* RSRC_A (global) DESCA[ RSRC_ ] The process row over which the first
* row of the matrix A is distributed,
* NPROW > RSRC_A >= 0.
* CSRC_A (global) DESCA[ CSRC_ ] The process column over which the
* first column of A is distributed.
* NPCOL > CSRC_A >= 0.
* LLD_A (local) DESCA[ LLD_ ] The leading dimension of the local
* array storing the local blocks of
* the distributed matrix A,
* IF( Lc( 1, N_A ) > 0 )
* LLD_A >= MAX( 1, Lr( 1, M_A ) )
* ELSE
* LLD_A >= 1.
*
* Let K be the number of rows of a matrix A starting at the global in-
* dex IA,i.e, A( IA:IA+K-1, : ). Lr( IA, K ) denotes the number of rows
* that the process of row coordinate MYROW ( 0 <= MYROW < NPROW ) would
* receive if these K rows were distributed over NPROW processes. If K
* is the number of columns of a matrix A starting at the global index
* JA, i.e, A( :, JA:JA+K-1, : ), Lc( JA, K ) denotes the number of co-
* lumns that the process MYCOL ( 0 <= MYCOL < NPCOL ) would receive if
* these K columns were distributed over NPCOL processes.
*
* The values of Lr() and Lc() may be determined via a call to the func-
* tion PB_Cnumroc:
* Lr( IA, K ) = PB_Cnumroc( K, IA, IMB_A, MB_A, MYROW, RSRC_A, NPROW )
* Lc( JA, K ) = PB_Cnumroc( K, JA, INB_A, NB_A, MYCOL, CSRC_A, NPCOL )
*
* Arguments
* =========
*
* DESC (global and local output) INTEGER array
* On entry, DESC is an array of dimension DLEN_. DESC is the
* array descriptor to be set.
*
* M (global input) INTEGER
* On entry, M specifies the number of rows of the matrix.
* M must be at least zero.
*
* N (global input) INTEGER
* On entry, N specifies the number of columns of the matrix.
* N must be at least zero.
*
* IMB (global input) INTEGER
* On entry, IMB specifies the row size of the first block of
* the global matrix distribution. IMB must be at least one.
*
* INB (global input) INTEGER
* On entry, INB specifies the column size of the first block
* of the global matrix distribution. INB must be at least one.
*
* MB (global input) INTEGER
* On entry, MB specifies the row size of the blocks used to
* partition the matrix. MB must be at least one.
*
* NB (global input) INTEGER
* On entry, NB specifies the column size of the blocks used to
* partition the matrix. NB must be at least one.
*
* RSRC (global input) INTEGER
* On entry, RSRC specifies the row coordinate of the process
* that possesses the first row of the matrix. When RSRC = -1,
* the data is not distributed but replicated, otherwise RSRC
* must be at least zero and strictly less than NPROW.
*
* CSRC (global input) INTEGER
* On entry, CSRC specifies the column coordinate of the pro-
* cess that possesses the first column of the matrix. When
* CSRC = -1, the data is not distributed but replicated, other-
* wise CSRC must be at least zero and strictly less than NPCOL.
*
* CTXT (local input) INTEGER
* On entry, CTXT specifies the BLACS context handle, indicating
* the global communication context. The value of the context
* itself is local.
*
* LLD (local input) INTEGER
* On entry, LLD specifies the leading dimension of the local
* array storing the local entries of the matrix. LLD must be at
* least MAX( 1, Lr(1,M) ).
*
* -- Written on April 1, 1998 by
* Antoine Petitet, University of Tennessee, Knoxville 37996, USA.
*
* ---------------------------------------------------------------------
*/
/* ..
* .. Executable Statements ..
*
*/
DESC[DTYPE_] = BLOCK_CYCLIC_2D_INB;
DESC[CTXT_ ] = CTXT;
DESC[M_ ] = M;
DESC[N_ ] = N;
DESC[IMB_ ] = IMB;
DESC[INB_ ] = INB;
DESC[MB_ ] = MB;
DESC[NB_ ] = NB;
DESC[RSRC_ ] = RSRC;
DESC[CSRC_ ] = CSRC;
DESC[LLD_ ] = LLD;
/*
* End of PB_Cdescset
*/
}
