SUBROUTINE DESCSET( DESC, M, N, MB, NB, IRSRC, ICSRC, ICTXT, $ LLD )
*
* -- ScaLAPACK tools routine (version 1.5) --
* University of Tennessee, Knoxville, Oak Ridge National Laboratory, * and University of California, Berkeley. * May 1, 1997 * * .. Scalar Arguments .. INTEGER ICSRC, ICTXT, IRSRC, LLD, M, MB, N, NB * .. * .. Array Arguments .. INTEGER DESC( * ) * ..
*
* Purpose
* the BLACS process grid A is distribu- * ted over. The context itself is glo- * bal, but the handle (the integer * value) may vary. * M_A (global) DESCA( M_ ) The number of rows in the global * array A. * N_A (global) DESCA( N_ ) The number of columns in the global * array A. * MB_A (global) DESCA( MB_ ) The blocking factor used to distribute * the rows of the array. * NB_A (global) DESCA( NB_ ) The blocking factor used to distribute * the columns of the array. * RSRC_A (global) DESCA( RSRC_ ) The process row over which the first * row of the array A is distributed. * CSRC_A (global) DESCA( CSRC_ ) The process column over which the * first column of the array A is * distributed. * LLD_A (local) DESCA( LLD_ ) The leading dimension of the local * array. LLD_A >= MAX(1,LOCr(M_A)).
*
* Let K be the number of rows or columns of a distributed matrix,
* and assume that its process grid has dimension p x q.
* LOCr( K ) denotes the number of elements of K that a process
* would receive if K were distributed over the p processes of its
* process column.
* Similarly, LOCc( K ) denotes the number of elements of K that a
* process would receive if K were distributed over the q processes of
* its process row.
* The values of LOCr() and LOCc() may be determined via a call to the
* ScaLAPACK tool function, NUMROC:
* LOCr( M ) = NUMROC( M, MB_A, MYROW, RSRC_A, NPROW ), * LOCc( N ) = NUMROC( N, NB_A, MYCOL, CSRC_A, NPCOL ). * An upper bound for these quantities may be computed by: * LOCr( M ) <= ceil( ceil(M/MB_A)/NPROW )*MB_A * LOCc( N ) <= ceil( ceil(N/NB_A)/NPCOL )*NB_A
*
* Arguments
* M (global input) INTEGER * The number of rows in the distributed matrix. M >= 0. * * N (global input) INTEGER * The number of columns in the distributed matrix. N >= 0. * * MB (global input) INTEGER * The blocking factor used to distribute the rows of the * matrix. MB >= 1. * * NB (global input) INTEGER * The blocking factor used to distribute the columns of the * matrix. NB >= 1.
*
* IRSRC (global input) INTEGER
* The process row over which the first row of the matrix is * distributed. 0 <= IRSRC < NPROW.
*
* ICSRC (global input) INTEGER
* The process column over which the first column of the * matrix is distributed. 0 <= ICSRC < NPCOL.
*
* ICTXT (global input) INTEGER
* The BLACS context handle, indicating the global context of * the operation on the matrix. The context itself is global. * * LLD (local input) INTEGER * The leading dimension of the local array storing the local * blocks of the distributed matrix. LLD >= MAX(1,LOCr(M)).
*
* .. Parameters .. INTEGER BLOCK_CYCLIC_2D, CSRC_, CTXT_, DLEN_, DTYPE_, $ LLD_, MB_, M_, NB_, N_, RSRC_ PARAMETER ( BLOCK_CYCLIC_2D = 1, DLEN_ = 9, DTYPE_ = 1, $ CTXT_ = 2, M_ = 3, N_ = 4, MB_ = 5, NB_ = 6, $ RSRC_ = 7, CSRC_ = 8, LLD_ = 9 ) * .. * * .. Executable Statements .. * DESC( DTYPE_ ) = BLOCK_CYCLIC_2D DESC( M_ ) = M DESC( N_ ) = N DESC( MB_ ) = MB DESC( NB_ ) = NB DESC( RSRC_ ) = IRSRC DESC( CSRC_ ) = ICSRC DESC( CTXT_ ) = ICTXT DESC( LLD_ ) = LLD * RETURN * * End DESCSET * END