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*
*
SUBROUTINE PSLASIZESYEV( JOBZ, N, DESCA, MINSIZE )
*
*
* -- ScaLAPACK routine (version 1.7) --
* University of Tennessee, Knoxville, Oak Ridge National Laboratory,
* and University of California, Berkeley.
* May 1, 1997
*
* .. Scalar Arguments ..
CHARACTER JOBZ
INTEGER MINSIZE, N
* ..
* .. Array Arguments ..
INTEGER DESCA( * )
* ..
*
* Purpose
* =======
*
* PSLASIZESYEV computes the amount of memory needed by PSSYEV
* to calculate:
* 1) Eigenvectors and eigenvalues if JOBZ = 'V'
* 2) Eigenvalues only if JOBZ = 'N'
*
* Arguments
* =========
*
* NP = the number of rows local to a given process.
* NQ = the number of columns local to a given process.
*
* JOBZ (global input) CHARACTER*1
* Specifies whether or not to compute the eigenvectors:
* = 'N': Compute eigenvalues only.
* = 'V': Compute eigenvalues and eigenvectors.
*
* N (global input) INTEGER
* Size of the matrix to be tested. (global size)
*
* DESCA (global input) INTEGER array dimension ( DLEN_ )
*
* MINSIZE (global output) INTEGER
* Workspace required for PSSYEV to:
* 1) Eigenvectors and eigenvalues if JOBZ = 'V'
* 2) Eigenvalues only if JOBZ = 'N'
*
*
* .. Parameters ..
INTEGER BLOCK_CYCLIC_2D, DLEN_, DTYPE_, CTXT_, M_, N_,
$ MB_, NB_, RSRC_, CSRC_, LLD_
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 )
* ..
* .. Local Scalars ..
LOGICAL WANTZ
INTEGER CONTEXTC, CSRC_A, IACOL, IAROW, ICOFFA, IROFFA,
$ LCM, LCMQ, LDC, MQ0, MYCOL, MYPCOLC, MYPROWC,
$ MYROW, NB, NN, NP, NP0, NPCOL, NPCOLC, NPROCS,
$ NPROW, NPROWC, NQ, NRC, QRMEM, RSRC_A,
$ SIZEMQRLEFT, SIZEMQRRIGHT
* ..
* .. External Functions ..
*
*
LOGICAL LSAME
INTEGER ILCM, INDXG2P, NUMROC, SL_GRIDRESHAPE
EXTERNAL ILCM, INDXG2P, LSAME, NUMROC, SL_GRIDRESHAPE
* ..
* .. External Subroutines ..
EXTERNAL BLACS_GRIDINFO, BLACS_GRIDEXIT
* ..
* .. Intrinsic Functions ..
INTRINSIC MAX
* ..
* .. Executable Statements ..
* This is just to keep ftnchek happy
IF( BLOCK_CYCLIC_2D*CSRC_*CTXT_*DLEN_*DTYPE_*LLD_*MB_*M_*NB_*N_*
$ RSRC_.LT.0 )RETURN
*
CALL BLACS_GRIDINFO( DESCA( CTXT_ ), NPROW, NPCOL, MYROW, MYCOL )
NB = DESCA( MB_ )
N = DESCA( M_ )
RSRC_A = DESCA( RSRC_ )
CSRC_A = DESCA( CSRC_ )
LCM = ILCM( NPROW, NPCOL )
LCMQ = LCM / NPCOL
IROFFA = 0
ICOFFA = 0
IAROW = INDXG2P( 1, NB, MYROW, RSRC_A, NPROW )
IACOL = INDXG2P( 1, NB, MYCOL, CSRC_A, NPCOL )
NP = NUMROC( N+IROFFA, NB, MYROW, IAROW, NPROW )
NQ = NUMROC( N+ICOFFA, NB, MYCOL, IACOL, NPCOL )
SIZEMQRLEFT = MAX( ( NB*( NB-1 ) ) / 2, ( NP+NQ )*NB ) + NB*NB
SIZEMQRRIGHT = MAX( ( NB*( NB-1 ) ) / 2,
$ ( NQ+MAX( NP+NUMROC( NUMROC( N+ICOFFA, NB, 0, 0,
$ NPCOL ), NB, 0, 0, LCMQ ), NP ) )*NB ) + NB*NB
NN = MAX( N, NB, 2 )
NP0 = NUMROC( NN, NB, 0, 0, NPROW )
MQ0 = NUMROC( NN, NB, 0, 0, NPCOL )
NPROCS = NPROW*NPCOL
WANTZ = LSAME( JOBZ, 'V' )
LDC = 0
*
* Create the new context that is used in PSSYEV
*
IF( WANTZ ) THEN
CONTEXTC = SL_GRIDRESHAPE( DESCA( CTXT_ ), 0, 1, 1, NPROCS, 1 )
CALL BLACS_GRIDINFO( CONTEXTC, NPROWC, NPCOLC, MYPROWC,
$ MYPCOLC )
NRC = NUMROC( N, NB, MYPROWC, 0, NPROCS)
LDC = MAX( 1, NRC )
CALL BLACS_GRIDEXIT( CONTEXTC )
END IF
*
* Compute the total amount of space needed
*
IF( WANTZ ) THEN
QRMEM = 5*N + MAX( 2*NP0 +MQ0 + NB*NN, 2*NN-2 ) + N*LDC
MINSIZE = MAX ( SIZEMQRLEFT, SIZEMQRRIGHT, QRMEM )
ELSE
MINSIZE = 5*N + 2*NP0 +MQ0 + NB*NN
END IF
*
RETURN
*
* End of PSLASIZESYEV
*
END
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