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*> \brief \b DLASDT creates a tree of subproblems for bidiagonal divide and conquer. Used by sbdsdc.
*
* =========== DOCUMENTATION ===========
*
* Online html documentation available at
* http://www.netlib.org/lapack/explore-html/
*
*> \htmlonly
*> Download DLASDT + dependencies
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlasdt.f">
*> [TGZ]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlasdt.f">
*> [ZIP]</a>
*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlasdt.f">
*> [TXT]</a>
*> \endhtmlonly
*
* Definition:
* ===========
*
* SUBROUTINE DLASDT( N, LVL, ND, INODE, NDIML, NDIMR, MSUB )
*
* .. Scalar Arguments ..
* INTEGER LVL, MSUB, N, ND
* ..
* .. Array Arguments ..
* INTEGER INODE( * ), NDIML( * ), NDIMR( * )
* ..
*
*
*> \par Purpose:
* =============
*>
*> \verbatim
*>
*> DLASDT creates a tree of subproblems for bidiagonal divide and
*> conquer.
*> \endverbatim
*
* Arguments:
* ==========
*
*> \param[in] N
*> \verbatim
*> N is INTEGER
*> On entry, the number of diagonal elements of the
*> bidiagonal matrix.
*> \endverbatim
*>
*> \param[out] LVL
*> \verbatim
*> LVL is INTEGER
*> On exit, the number of levels on the computation tree.
*> \endverbatim
*>
*> \param[out] ND
*> \verbatim
*> ND is INTEGER
*> On exit, the number of nodes on the tree.
*> \endverbatim
*>
*> \param[out] INODE
*> \verbatim
*> INODE is INTEGER array, dimension ( N )
*> On exit, centers of subproblems.
*> \endverbatim
*>
*> \param[out] NDIML
*> \verbatim
*> NDIML is INTEGER array, dimension ( N )
*> On exit, row dimensions of left children.
*> \endverbatim
*>
*> \param[out] NDIMR
*> \verbatim
*> NDIMR is INTEGER array, dimension ( N )
*> On exit, row dimensions of right children.
*> \endverbatim
*>
*> \param[in] MSUB
*> \verbatim
*> MSUB is INTEGER
*> On entry, the maximum row dimension each subproblem at the
*> bottom of the tree can be of.
*> \endverbatim
*
* Authors:
* ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date December 2016
*
*> \ingroup OTHERauxiliary
*
*> \par Contributors:
* ==================
*>
*> Ming Gu and Huan Ren, Computer Science Division, University of
*> California at Berkeley, USA
*>
* =====================================================================
SUBROUTINE DLASDT( N, LVL, ND, INODE, NDIML, NDIMR, MSUB )
*
* -- LAPACK auxiliary routine (version 3.7.0) --
* -- LAPACK is a software package provided by Univ. of Tennessee, --
* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
* December 2016
*
* .. Scalar Arguments ..
INTEGER LVL, MSUB, N, ND
* ..
* .. Array Arguments ..
INTEGER INODE( * ), NDIML( * ), NDIMR( * )
* ..
*
* =====================================================================
*
* .. Parameters ..
DOUBLE PRECISION TWO
PARAMETER ( TWO = 2.0D+0 )
* ..
* .. Local Scalars ..
INTEGER I, IL, IR, LLST, MAXN, NCRNT, NLVL
DOUBLE PRECISION TEMP
* ..
* .. Intrinsic Functions ..
INTRINSIC DBLE, INT, LOG, MAX
* ..
* .. Executable Statements ..
*
* Find the number of levels on the tree.
*
MAXN = MAX( 1, N )
TEMP = LOG( DBLE( MAXN ) / DBLE( MSUB+1 ) ) / LOG( TWO )
LVL = INT( TEMP ) + 1
*
I = N / 2
INODE( 1 ) = I + 1
NDIML( 1 ) = I
NDIMR( 1 ) = N - I - 1
IL = 0
IR = 1
LLST = 1
DO 20 NLVL = 1, LVL - 1
*
* Constructing the tree at (NLVL+1)-st level. The number of
* nodes created on this level is LLST * 2.
*
DO 10 I = 0, LLST - 1
IL = IL + 2
IR = IR + 2
NCRNT = LLST + I
NDIML( IL ) = NDIML( NCRNT ) / 2
NDIMR( IL ) = NDIML( NCRNT ) - NDIML( IL ) - 1
INODE( IL ) = INODE( NCRNT ) - NDIMR( IL ) - 1
NDIML( IR ) = NDIMR( NCRNT ) / 2
NDIMR( IR ) = NDIMR( NCRNT ) - NDIML( IR ) - 1
INODE( IR ) = INODE( NCRNT ) + NDIML( IR ) + 1
10 CONTINUE
LLST = LLST*2
20 CONTINUE
ND = LLST*2 - 1
*
RETURN
*
* End of DLASDT
*
END
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