Return to dlasdt.f CVS log

Up to [local] / rpl / lapack / lapack

Annotation of rpl/lapack/lapack/dlasdt.f, revision 1.19

1.12      bertrand    1: *> \brief \b DLASDT creates a tree of subproblems for bidiagonal divide and conquer. Used by sbdsdc.
1.9       bertrand    2: *
                      3: *  =========== DOCUMENTATION ===========
                      4: *
1.16      bertrand    5: * Online html documentation available at
                      6: *            http://www.netlib.org/lapack/explore-html/
1.9       bertrand    7: *
                      8: *> \htmlonly
1.16      bertrand    9: *> Download DLASDT + dependencies
                     10: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlasdt.f">
                     11: *> [TGZ]</a>
                     12: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlasdt.f">
                     13: *> [ZIP]</a>
                     14: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlasdt.f">
1.9       bertrand   15: *> [TXT]</a>
1.16      bertrand   16: *> \endhtmlonly
1.9       bertrand   17: *
                     18: *  Definition:
                     19: *  ===========
                     20: *
                     21: *       SUBROUTINE DLASDT( N, LVL, ND, INODE, NDIML, NDIMR, MSUB )
1.16      bertrand   22: *
1.9       bertrand   23: *       .. Scalar Arguments ..
                     24: *       INTEGER            LVL, MSUB, N, ND
                     25: *       ..
                     26: *       .. Array Arguments ..
                     27: *       INTEGER            INODE( * ), NDIML( * ), NDIMR( * )
                     28: *       ..
1.16      bertrand   29: *
1.9       bertrand   30: *
                     31: *> \par Purpose:
                     32: *  =============
                     33: *>
                     34: *> \verbatim
                     35: *>
                     36: *> DLASDT creates a tree of subproblems for bidiagonal divide and
                     37: *> conquer.
                     38: *> \endverbatim
                     39: *
                     40: *  Arguments:
                     41: *  ==========
                     42: *
                     43: *> \param[in] N
                     44: *> \verbatim
                     45: *>          N is INTEGER
                     46: *>          On entry, the number of diagonal elements of the
                     47: *>          bidiagonal matrix.
                     48: *> \endverbatim
                     49: *>
                     50: *> \param[out] LVL
                     51: *> \verbatim
                     52: *>          LVL is INTEGER
                     53: *>          On exit, the number of levels on the computation tree.
                     54: *> \endverbatim
                     55: *>
                     56: *> \param[out] ND
                     57: *> \verbatim
                     58: *>          ND is INTEGER
                     59: *>          On exit, the number of nodes on the tree.
                     60: *> \endverbatim
                     61: *>
                     62: *> \param[out] INODE
                     63: *> \verbatim
                     64: *>          INODE is INTEGER array, dimension ( N )
                     65: *>          On exit, centers of subproblems.
                     66: *> \endverbatim
                     67: *>
                     68: *> \param[out] NDIML
                     69: *> \verbatim
                     70: *>          NDIML is INTEGER array, dimension ( N )
                     71: *>          On exit, row dimensions of left children.
                     72: *> \endverbatim
                     73: *>
                     74: *> \param[out] NDIMR
                     75: *> \verbatim
                     76: *>          NDIMR is INTEGER array, dimension ( N )
                     77: *>          On exit, row dimensions of right children.
                     78: *> \endverbatim
                     79: *>
                     80: *> \param[in] MSUB
                     81: *> \verbatim
                     82: *>          MSUB is INTEGER
                     83: *>          On entry, the maximum row dimension each subproblem at the
                     84: *>          bottom of the tree can be of.
                     85: *> \endverbatim
                     86: *
                     87: *  Authors:
                     88: *  ========
                     89: *
1.16      bertrand   90: *> \author Univ. of Tennessee
                     91: *> \author Univ. of California Berkeley
                     92: *> \author Univ. of Colorado Denver
                     93: *> \author NAG Ltd.
1.9       bertrand   94: *
1.16      bertrand   95: *> \ingroup OTHERauxiliary
1.9       bertrand   96: *
                     97: *> \par Contributors:
                     98: *  ==================
                     99: *>
                    100: *>     Ming Gu and Huan Ren, Computer Science Division, University of
                    101: *>     California at Berkeley, USA
                    102: *>
                    103: *  =====================================================================
1.1       bertrand  104:       SUBROUTINE DLASDT( N, LVL, ND, INODE, NDIML, NDIMR, MSUB )
                    105: *
1.19    ! bertrand  106: *  -- LAPACK auxiliary routine --
1.1       bertrand  107: *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
                    108: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
                    109: *
                    110: *     .. Scalar Arguments ..
                    111:       INTEGER            LVL, MSUB, N, ND
                    112: *     ..
                    113: *     .. Array Arguments ..
                    114:       INTEGER            INODE( * ), NDIML( * ), NDIMR( * )
                    115: *     ..
                    116: *
                    117: *  =====================================================================
                    118: *
                    119: *     .. Parameters ..
                    120:       DOUBLE PRECISION   TWO
                    121:       PARAMETER          ( TWO = 2.0D+0 )
                    122: *     ..
                    123: *     .. Local Scalars ..
                    124:       INTEGER            I, IL, IR, LLST, MAXN, NCRNT, NLVL
                    125:       DOUBLE PRECISION   TEMP
                    126: *     ..
                    127: *     .. Intrinsic Functions ..
                    128:       INTRINSIC          DBLE, INT, LOG, MAX
                    129: *     ..
                    130: *     .. Executable Statements ..
                    131: *
                    132: *     Find the number of levels on the tree.
                    133: *
                    134:       MAXN = MAX( 1, N )
                    135:       TEMP = LOG( DBLE( MAXN ) / DBLE( MSUB+1 ) ) / LOG( TWO )
                    136:       LVL = INT( TEMP ) + 1
                    137: *
                    138:       I = N / 2
                    139:       INODE( 1 ) = I + 1
                    140:       NDIML( 1 ) = I
                    141:       NDIMR( 1 ) = N - I - 1
                    142:       IL = 0
                    143:       IR = 1
                    144:       LLST = 1
                    145:       DO 20 NLVL = 1, LVL - 1
                    146: *
                    147: *        Constructing the tree at (NLVL+1)-st level. The number of
                    148: *        nodes created on this level is LLST * 2.
                    149: *
                    150:          DO 10 I = 0, LLST - 1
                    151:             IL = IL + 2
                    152:             IR = IR + 2
                    153:             NCRNT = LLST + I
                    154:             NDIML( IL ) = NDIML( NCRNT ) / 2
                    155:             NDIMR( IL ) = NDIML( NCRNT ) - NDIML( IL ) - 1
                    156:             INODE( IL ) = INODE( NCRNT ) - NDIMR( IL ) - 1
                    157:             NDIML( IR ) = NDIMR( NCRNT ) / 2
                    158:             NDIMR( IR ) = NDIMR( NCRNT ) - NDIML( IR ) - 1
                    159:             INODE( IR ) = INODE( NCRNT ) + NDIML( IR ) + 1
                    160:    10    CONTINUE
                    161:          LLST = LLST*2
                    162:    20 CONTINUE
                    163:       ND = LLST*2 - 1
                    164: *
                    165:       RETURN
                    166: *
                    167: *     End of DLASDT
                    168: *
                    169:       END