root / src / lapack / double / dlasdt.f @ 2
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| 1 | 1 | equemene | SUBROUTINE DLASDT( N, LVL, ND, INODE, NDIML, NDIMR, MSUB ) |
|---|---|---|---|
| 2 | 1 | equemene | * |
| 3 | 1 | equemene | * -- LAPACK auxiliary routine (version 3.2.2) -- |
| 4 | 1 | equemene | * -- LAPACK is a software package provided by Univ. of Tennessee, -- |
| 5 | 1 | equemene | * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- |
| 6 | 1 | equemene | * June 2010 |
| 7 | 1 | equemene | * |
| 8 | 1 | equemene | * .. Scalar Arguments .. |
| 9 | 1 | equemene | INTEGER LVL, MSUB, N, ND |
| 10 | 1 | equemene | * .. |
| 11 | 1 | equemene | * .. Array Arguments .. |
| 12 | 1 | equemene | INTEGER INODE( * ), NDIML( * ), NDIMR( * ) |
| 13 | 1 | equemene | * .. |
| 14 | 1 | equemene | * |
| 15 | 1 | equemene | * Purpose |
| 16 | 1 | equemene | * ======= |
| 17 | 1 | equemene | * |
| 18 | 1 | equemene | * DLASDT creates a tree of subproblems for bidiagonal divide and |
| 19 | 1 | equemene | * conquer. |
| 20 | 1 | equemene | * |
| 21 | 1 | equemene | * Arguments |
| 22 | 1 | equemene | * ========= |
| 23 | 1 | equemene | * |
| 24 | 1 | equemene | * N (input) INTEGER |
| 25 | 1 | equemene | * On entry, the number of diagonal elements of the |
| 26 | 1 | equemene | * bidiagonal matrix. |
| 27 | 1 | equemene | * |
| 28 | 1 | equemene | * LVL (output) INTEGER |
| 29 | 1 | equemene | * On exit, the number of levels on the computation tree. |
| 30 | 1 | equemene | * |
| 31 | 1 | equemene | * ND (output) INTEGER |
| 32 | 1 | equemene | * On exit, the number of nodes on the tree. |
| 33 | 1 | equemene | * |
| 34 | 1 | equemene | * INODE (output) INTEGER array, dimension ( N ) |
| 35 | 1 | equemene | * On exit, centers of subproblems. |
| 36 | 1 | equemene | * |
| 37 | 1 | equemene | * NDIML (output) INTEGER array, dimension ( N ) |
| 38 | 1 | equemene | * On exit, row dimensions of left children. |
| 39 | 1 | equemene | * |
| 40 | 1 | equemene | * NDIMR (output) INTEGER array, dimension ( N ) |
| 41 | 1 | equemene | * On exit, row dimensions of right children. |
| 42 | 1 | equemene | * |
| 43 | 1 | equemene | * MSUB (input) INTEGER |
| 44 | 1 | equemene | * On entry, the maximum row dimension each subproblem at the |
| 45 | 1 | equemene | * bottom of the tree can be of. |
| 46 | 1 | equemene | * |
| 47 | 1 | equemene | * Further Details |
| 48 | 1 | equemene | * =============== |
| 49 | 1 | equemene | * |
| 50 | 1 | equemene | * Based on contributions by |
| 51 | 1 | equemene | * Ming Gu and Huan Ren, Computer Science Division, University of |
| 52 | 1 | equemene | * California at Berkeley, USA |
| 53 | 1 | equemene | * |
| 54 | 1 | equemene | * ===================================================================== |
| 55 | 1 | equemene | * |
| 56 | 1 | equemene | * .. Parameters .. |
| 57 | 1 | equemene | DOUBLE PRECISION TWO |
| 58 | 1 | equemene | PARAMETER ( TWO = 2.0D+0 ) |
| 59 | 1 | equemene | * .. |
| 60 | 1 | equemene | * .. Local Scalars .. |
| 61 | 1 | equemene | INTEGER I, IL, IR, LLST, MAXN, NCRNT, NLVL |
| 62 | 1 | equemene | DOUBLE PRECISION TEMP |
| 63 | 1 | equemene | * .. |
| 64 | 1 | equemene | * .. Intrinsic Functions .. |
| 65 | 1 | equemene | INTRINSIC DBLE, INT, LOG, MAX |
| 66 | 1 | equemene | * .. |
| 67 | 1 | equemene | * .. Executable Statements .. |
| 68 | 1 | equemene | * |
| 69 | 1 | equemene | * Find the number of levels on the tree. |
| 70 | 1 | equemene | * |
| 71 | 1 | equemene | MAXN = MAX( 1, N ) |
| 72 | 1 | equemene | TEMP = LOG( DBLE( MAXN ) / DBLE( MSUB+1 ) ) / LOG( TWO ) |
| 73 | 1 | equemene | LVL = INT( TEMP ) + 1 |
| 74 | 1 | equemene | * |
| 75 | 1 | equemene | I = N / 2 |
| 76 | 1 | equemene | INODE( 1 ) = I + 1 |
| 77 | 1 | equemene | NDIML( 1 ) = I |
| 78 | 1 | equemene | NDIMR( 1 ) = N - I - 1 |
| 79 | 1 | equemene | IL = 0 |
| 80 | 1 | equemene | IR = 1 |
| 81 | 1 | equemene | LLST = 1 |
| 82 | 1 | equemene | DO 20 NLVL = 1, LVL - 1 |
| 83 | 1 | equemene | * |
| 84 | 1 | equemene | * Constructing the tree at (NLVL+1)-st level. The number of |
| 85 | 1 | equemene | * nodes created on this level is LLST * 2. |
| 86 | 1 | equemene | * |
| 87 | 1 | equemene | DO 10 I = 0, LLST - 1 |
| 88 | 1 | equemene | IL = IL + 2 |
| 89 | 1 | equemene | IR = IR + 2 |
| 90 | 1 | equemene | NCRNT = LLST + I |
| 91 | 1 | equemene | NDIML( IL ) = NDIML( NCRNT ) / 2 |
| 92 | 1 | equemene | NDIMR( IL ) = NDIML( NCRNT ) - NDIML( IL ) - 1 |
| 93 | 1 | equemene | INODE( IL ) = INODE( NCRNT ) - NDIMR( IL ) - 1 |
| 94 | 1 | equemene | NDIML( IR ) = NDIMR( NCRNT ) / 2 |
| 95 | 1 | equemene | NDIMR( IR ) = NDIMR( NCRNT ) - NDIML( IR ) - 1 |
| 96 | 1 | equemene | INODE( IR ) = INODE( NCRNT ) + NDIML( IR ) + 1 |
| 97 | 1 | equemene | 10 CONTINUE |
| 98 | 1 | equemene | LLST = LLST*2 |
| 99 | 1 | equemene | 20 CONTINUE |
| 100 | 1 | equemene | ND = LLST*2 - 1 |
| 101 | 1 | equemene | * |
| 102 | 1 | equemene | RETURN |
| 103 | 1 | equemene | * |
| 104 | 1 | equemene | * End of DLASDT |
| 105 | 1 | equemene | * |
| 106 | 1 | equemene | END |