ScaLAPACK
2.0.2
ScaLAPACK: Scalable Linear Algebra PACKage

#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 blockcyclicly 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_AIMB_A rows of A, * MB_A > 0. * NB_A (global) DESCA[ NB_ ] The blocking factor used to distri * bute the last N_AINB_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+K1, : ). 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+K1, : ), 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 */ }