1SLAEDA(1)                LAPACK routine (version 3.1)                SLAEDA(1)
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NAME

6       SLAEDA  -  the Z vector corresponding to the merge step in the CURLVLth
7       step of the merge process with TLVLS steps for the CURPBMth problem
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SYNOPSIS

10       SUBROUTINE SLAEDA( N, TLVLS, CURLVL, CURPBM, PRMPTR, PERM, GIVPTR, GIV‐
11                          COL, GIVNUM, Q, QPTR, Z, ZTEMP, INFO )
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13           INTEGER        CURLVL, CURPBM, INFO, N, TLVLS
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15           INTEGER        GIVCOL( 2, * ), GIVPTR( * ), PERM( * ), PRMPTR( * ),
16                          QPTR( * )
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18           REAL           GIVNUM( 2, * ), Q( * ), Z( * ), ZTEMP( * )
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PURPOSE

21       SLAEDA computes the Z vector corresponding to the  merge  step  in  the
22       CURLVLth  step  of  the merge process with TLVLS steps for the CURPBMth
23       problem.
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ARGUMENTS

27       N      (input) INTEGER
28              The dimension of the symmetric tridiagonal matrix.  N >= 0.
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30       TLVLS  (input) INTEGER
31              The total number of merging levels in  the  overall  divide  and
32              conquer tree.
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34              CURLVL  (input)  INTEGER  The current level in the overall merge
35              routine, 0 <= curlvl <= tlvls.
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37              CURPBM (input) INTEGER The current problem in the current  level
38              in  the overall merge routine (counting from upper left to lower
39              right).
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41              PRMPTR (input) INTEGER array, dimension (N lg N) Contains a list
42              of  pointers  which indicate where in PERM a level's permutation
43              is stored.  PRMPTR(i+1) - PRMPTR(i) indicates the  size  of  the
44              permutation  and incidentally the size of the full, non-deflated
45              problem.
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47       PERM   (input) INTEGER array, dimension (N lg N)
48              Contains the permutations (from deflation  and  sorting)  to  be
49              applied to each eigenblock.
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51              GIVPTR (input) INTEGER array, dimension (N lg N) Contains a list
52              of pointers which indicate where  in  GIVCOL  a  level's  Givens
53              rotations  are  stored.   GIVPTR(i+1)  - GIVPTR(i) indicates the
54              number of Givens rotations.
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56              GIVCOL (input) INTEGER array, dimension (2, N lg N) Each pair of
57              numbers  indicates  a  pair of columns to take place in a Givens
58              rotation.
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60              GIVNUM (input) REAL array, dimension (2, N  lg  N)  Each  number
61              indicates  the  S  value  to be used in the corresponding Givens
62              rotation.
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64       Q      (input) REAL array, dimension (N**2)
65              Contains the square eigenblocks from previous levels, the start‐
66              ing positions for blocks are given by QPTR.
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68       QPTR   (input) INTEGER array, dimension (N+2)
69              Contains  a list of pointers which indicate where in Q an eigen‐
70              block is stored.  SQRT( QPTR(i+1) - QPTR(i) ) indicates the size
71              of the block.
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73       Z      (output) REAL array, dimension (N)
74              On output this vector contains the updating vector (the last row
75              of the first sub-eigenvector matrix and the  first  row  of  the
76              second sub-eigenvector matrix).
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78       ZTEMP  (workspace) REAL array, dimension (N)
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80       INFO   (output) INTEGER
81              = 0:  successful exit.
82              < 0:  if INFO = -i, the i-th argument had an illegal value.
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FURTHER DETAILS

85       Based on contributions by
86          Jeff Rutter, Computer Science Division, University of California
87          at Berkeley, USA
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92 LAPACK routine (version 3.1)    November 2006                       SLAEDA(1)