Annotation of rpl/lapack/lapack/dlasdt.f, revision 1.17
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: *> \date December 2016
1.9 bertrand 96: *
1.16 bertrand 97: *> \ingroup OTHERauxiliary
1.9 bertrand 98: *
99: *> \par Contributors:
100: * ==================
101: *>
102: *> Ming Gu and Huan Ren, Computer Science Division, University of
103: *> California at Berkeley, USA
104: *>
105: * =====================================================================
1.1 bertrand 106: SUBROUTINE DLASDT( N, LVL, ND, INODE, NDIML, NDIMR, MSUB )
107: *
1.16 bertrand 108: * -- LAPACK auxiliary routine (version 3.7.0) --
1.1 bertrand 109: * -- LAPACK is a software package provided by Univ. of Tennessee, --
110: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
1.16 bertrand 111: * December 2016
1.1 bertrand 112: *
113: * .. Scalar Arguments ..
114: INTEGER LVL, MSUB, N, ND
115: * ..
116: * .. Array Arguments ..
117: INTEGER INODE( * ), NDIML( * ), NDIMR( * )
118: * ..
119: *
120: * =====================================================================
121: *
122: * .. Parameters ..
123: DOUBLE PRECISION TWO
124: PARAMETER ( TWO = 2.0D+0 )
125: * ..
126: * .. Local Scalars ..
127: INTEGER I, IL, IR, LLST, MAXN, NCRNT, NLVL
128: DOUBLE PRECISION TEMP
129: * ..
130: * .. Intrinsic Functions ..
131: INTRINSIC DBLE, INT, LOG, MAX
132: * ..
133: * .. Executable Statements ..
134: *
135: * Find the number of levels on the tree.
136: *
137: MAXN = MAX( 1, N )
138: TEMP = LOG( DBLE( MAXN ) / DBLE( MSUB+1 ) ) / LOG( TWO )
139: LVL = INT( TEMP ) + 1
140: *
141: I = N / 2
142: INODE( 1 ) = I + 1
143: NDIML( 1 ) = I
144: NDIMR( 1 ) = N - I - 1
145: IL = 0
146: IR = 1
147: LLST = 1
148: DO 20 NLVL = 1, LVL - 1
149: *
150: * Constructing the tree at (NLVL+1)-st level. The number of
151: * nodes created on this level is LLST * 2.
152: *
153: DO 10 I = 0, LLST - 1
154: IL = IL + 2
155: IR = IR + 2
156: NCRNT = LLST + I
157: NDIML( IL ) = NDIML( NCRNT ) / 2
158: NDIMR( IL ) = NDIML( NCRNT ) - NDIML( IL ) - 1
159: INODE( IL ) = INODE( NCRNT ) - NDIMR( IL ) - 1
160: NDIML( IR ) = NDIMR( NCRNT ) / 2
161: NDIMR( IR ) = NDIMR( NCRNT ) - NDIML( IR ) - 1
162: INODE( IR ) = INODE( NCRNT ) + NDIML( IR ) + 1
163: 10 CONTINUE
164: LLST = LLST*2
165: 20 CONTINUE
166: ND = LLST*2 - 1
167: *
168: RETURN
169: *
170: * End of DLASDT
171: *
172: END
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