ScaLAPACK 2.1  2.1 ScaLAPACK: Scalable Linear Algebra PACKage
pdlasizesyev.f
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1 *
2 *
3  SUBROUTINE pdlasizesyev( JOBZ, N, DESCA, MINSIZE )
4 *
5 *
6 * -- ScaLAPACK routine (version 1.7) --
7 * University of Tennessee, Knoxville, Oak Ridge National Laboratory,
8 * and University of California, Berkeley.
9 * May 1, 1997
10 *
11 * .. Scalar Arguments ..
12  CHARACTER JOBZ
13  INTEGER MINSIZE, N
14 * ..
15 * .. Array Arguments ..
16  INTEGER DESCA( * )
17 * ..
18 *
19 * Purpose
20 * =======
21 *
22 * PDLASIZESYEV computes the amount of memory needed by PDSYEV
23 * to calculate:
24 * 1) Eigenvectors and eigenvalues if JOBZ = 'V'
25 * 2) Eigenvalues only if JOBZ = 'N'
26 *
27 * Arguments
28 * =========
29 *
30 * NP = the number of rows local to a given process.
31 * NQ = the number of columns local to a given process.
32 *
33 * JOBZ (global input) CHARACTER*1
34 * Specifies whether or not to compute the eigenvectors:
35 * = 'N': Compute eigenvalues only.
36 * = 'V': Compute eigenvalues and eigenvectors.
37 *
38 * N (global input) INTEGER
39 * Size of the matrix to be tested. (global size)
40 *
41 * DESCA (global input) INTEGER array dimension ( DLEN_ )
42 *
43 * MINSIZE (global output) INTEGER
44 * Workspace required for PDSYEV to:
45 * 1) Eigenvectors and eigenvalues if JOBZ = 'V'
46 * 2) Eigenvalues only if JOBZ = 'N'
47 *
48 *
49 * .. Parameters ..
50  INTEGER BLOCK_CYCLIC_2D, DLEN_, DTYPE_, CTXT_, M_, N_,
51  \$ MB_, NB_, RSRC_, CSRC_, LLD_
52  parameter( block_cyclic_2d = 1, dlen_ = 9, dtype_ = 1,
53  \$ ctxt_ = 2, m_ = 3, n_ = 4, mb_ = 5, nb_ = 6,
54  \$ rsrc_ = 7, csrc_ = 8, lld_ = 9 )
55 * ..
56 * .. Local Scalars ..
57  LOGICAL WANTZ
58  INTEGER CONTEXTC, CSRC_A, IACOL, IAROW, ICOFFA, IROFFA,
59  \$ LCM, LCMQ, LDC, MQ0, MYCOL, MYPCOLC, MYPROWC,
60  \$ MYROW, NB, NN, NP, NP0, NPCOL, NPCOLC, NPROCS,
61  \$ NPROW, NPROWC, NQ, NRC, QRMEM, RSRC_A,
62  \$ SIZEMQRLEFT, SIZEMQRRIGHT
63 * ..
64 * .. External Functions ..
65 *
66 *
67  LOGICAL LSAME
68  INTEGER ILCM, INDXG2P, NUMROC, SL_GRIDRESHAPE
69  EXTERNAL ilcm, indxg2p, lsame, numroc, sl_gridreshape
70 * ..
71 * .. External Subroutines ..
72  EXTERNAL blacs_gridinfo, blacs_gridexit
73 * ..
74 * .. Intrinsic Functions ..
75  INTRINSIC max
76 * ..
77 * .. Executable Statements ..
78 * This is just to keep ftnchek happy
79  IF( block_cyclic_2d*csrc_*ctxt_*dlen_*dtype_*lld_*mb_*m_*nb_*n_*
80  \$ rsrc_.LT.0 )RETURN
81 *
82  CALL blacs_gridinfo( desca( ctxt_ ), nprow, npcol, myrow, mycol )
83  nb = desca( mb_ )
84  n = desca( m_ )
85  rsrc_a = desca( rsrc_ )
86  csrc_a = desca( csrc_ )
87  lcm = ilcm( nprow, npcol )
88  lcmq = lcm / npcol
89  iroffa = 0
90  icoffa = 0
91  iarow = indxg2p( 1, nb, myrow, rsrc_a, nprow )
92  iacol = indxg2p( 1, nb, mycol, csrc_a, npcol )
93  np = numroc( n+iroffa, nb, myrow, iarow, nprow )
94  nq = numroc( n+icoffa, nb, mycol, iacol, npcol )
95  sizemqrleft = max( ( nb*( nb-1 ) ) / 2, ( np+nq )*nb ) + nb*nb
96  sizemqrright = max( ( nb*( nb-1 ) ) / 2,
97  \$ ( nq+max( np+numroc( numroc( n+icoffa, nb, 0, 0,
98  \$ npcol ), nb, 0, 0, lcmq ), np ) )*nb ) + nb*nb
99  nn = max( n, nb, 2 )
100  np0 = numroc( nn, nb, 0, 0, nprow )
101  mq0 = numroc( nn, nb, 0, 0, npcol )
102  nprocs = nprow*npcol
103  wantz = lsame( jobz, 'V' )
104  ldc = 0
105 *
106 * Create the new context that is used in PDSYEV
107 *
108  IF( wantz ) THEN
109  contextc = sl_gridreshape( desca( ctxt_ ), 0, 1, 1, nprocs, 1 )
110  CALL blacs_gridinfo( contextc, nprowc, npcolc, myprowc,
111  \$ mypcolc )
112  nrc = numroc( n, nb, myprowc, 0, nprocs)
113  ldc = max( 1, nrc )
114  CALL blacs_gridexit( contextc )
115  END IF
116
117 *
118 * Compute the total amount of space needed
119 *
120  IF( wantz ) THEN
121  qrmem = 5*n + max( 2*np0 +mq0 + nb*nn, 2*nn-2 ) + n*ldc
122  minsize = max( sizemqrleft, sizemqrright, qrmem )
123  ELSE
124  minsize = 5*n + 2*np0 +mq0 + nb*nn
125  END IF
126 *
127  RETURN
128 *
129 * End of PDLASIZESYEV
130 *
131  END
max
#define max(A, B)
Definition: pcgemr.c:180
pdlasizesyev
subroutine pdlasizesyev(JOBZ, N, DESCA, MINSIZE)
Definition: pdlasizesyev.f:4