# slaeda(3) [centos man page]

```slaeda.f(3)							      LAPACK							       slaeda.f(3)

NAME
slaeda.f -

SYNOPSIS
Functions/Subroutines
subroutine slaeda (N, TLVLS, CURLVL, CURPBM, PRMPTR, PERM, GIVPTR, GIVCOL, GIVNUM, Q, QPTR, Z, ZTEMP, INFO)
SLAEDA used by sstedc. Computes the Z vector determining the rank-one modification of the diagonal matrix. Used when the original
matrix is dense.

Function/Subroutine Documentation
subroutine slaeda (integerN, integerTLVLS, integerCURLVL, integerCURPBM, integer, dimension( * )PRMPTR, integer, dimension( * )PERM, integer,
dimension( * )GIVPTR, integer, dimension( 2, * )GIVCOL, real, dimension( 2, * )GIVNUM, real, dimension( * )Q, integer, dimension( * )QPTR,
real, dimension( * )Z, real, dimension( * )ZTEMP, integerINFO)
SLAEDA used by sstedc. Computes the Z vector determining the rank-one modification of the diagonal matrix. Used when the original matrix is
dense.

Purpose:

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

Parameters:
N

N is INTEGER
The dimension of the symmetric tridiagonal matrix.	N >= 0.

TLVLS

TLVLS is INTEGER
The total number of merging levels in the overall divide and
conquer tree.

CURLVL

CURLVL is INTEGER
The current level in the overall merge routine,
0 <= curlvl <= tlvls.

CURPBM

CURPBM is INTEGER
The current problem in the current level in the overall
merge routine (counting from upper left to lower right).

PRMPTR

PRMPTR is INTEGER array, dimension (N lg N)
Contains a list of pointers which indicate where in PERM a
level's permutation is stored.  PRMPTR(i+1) - PRMPTR(i)
indicates the size of the permutation and incidentally the
size of the full, non-deflated problem.

PERM

PERM is INTEGER array, dimension (N lg N)
Contains the permutations (from deflation and sorting) to be
applied to each eigenblock.

GIVPTR

GIVPTR is INTEGER array, dimension (N lg N)
Contains a list of pointers which indicate where in GIVCOL a
level's Givens rotations are stored.  GIVPTR(i+1) - GIVPTR(i)
indicates the number of Givens rotations.

GIVCOL

GIVCOL is INTEGER array, dimension (2, N lg N)
Each pair of numbers indicates a pair of columns to take place
in a Givens rotation.

GIVNUM

GIVNUM is REAL array, dimension (2, N lg N)
Each number indicates the S value to be used in the
corresponding Givens rotation.

Q

Q is REAL array, dimension (N**2)
Contains the square eigenblocks from previous levels, the
starting positions for blocks are given by QPTR.

QPTR

QPTR is INTEGER array, dimension (N+2)
Contains a list of pointers which indicate where in Q an
eigenblock is stored.  SQRT( QPTR(i+1) - QPTR(i) ) indicates
the size of the block.

Z

Z is REAL array, dimension (N)
On output this vector contains the updating vector (the last
row of the first sub-eigenvector matrix and the first row of
the second sub-eigenvector matrix).

ZTEMP

ZTEMP is REAL array, dimension (N)

INFO

INFO is INTEGER
= 0:  successful exit.
< 0:  if INFO = -i, the i-th argument had an illegal value.

Author:
Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:
September 2012

Contributors:
Jeff Rutter, Computer Science Division, University of California at Berkeley, USA

Definition at line 166 of file slaeda.f.

Author
Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.2							  Tue Sep 25 2012						       slaeda.f(3)```

## Check Out this Related Man Page

```DLAEDA(l)								 )								 DLAEDA(l)

NAME
DLAEDA  -  compute the Z vector corresponding to the merge step in the CURLVLth step of the merge process with TLVLS steps for the CURPBMth
problem

SYNOPSIS
SUBROUTINE DLAEDA( N, TLVLS, CURLVL, CURPBM, PRMPTR, PERM, GIVPTR, GIVCOL, GIVNUM, Q, QPTR, Z, ZTEMP, INFO )

INTEGER	  CURLVL, CURPBM, INFO, N, TLVLS

INTEGER	  GIVCOL( 2, * ), GIVPTR( * ), PERM( * ), PRMPTR( * ), QPTR( * )

DOUBLE	  PRECISION GIVNUM( 2, * ), Q( * ), Z( * ), ZTEMP( * )

PURPOSE
DLAEDA computes the Z vector corresponding to the merge step in the CURLVLth step of the merge process with TLVLS steps	for  the  CURPBMth
problem.

ARGUMENTS
N      (input) INTEGER
The dimension of the symmetric tridiagonal matrix.  N >= 0.

TLVLS  (input) INTEGER
The total number of merging levels in the overall divide and conquer tree.

CURLVL (input) INTEGER The current level in the overall merge routine, 0 <= curlvl <= tlvls.

CURPBM  (input)  INTEGER	The  current  problem in the current level in the overall merge routine (counting from upper left to lower
right).

PRMPTR (input) INTEGER array, dimension (N lg N) Contains a list of pointers which indicate where in PERM a level's  permutation	is
stored.  PRMPTR(i+1) - PRMPTR(i) indicates the size of the permutation and incidentally the size of the full, non-deflated problem.

PERM   (input) INTEGER array, dimension (N lg N)
Contains the permutations (from deflation and sorting) to be applied to each eigenblock.

GIVPTR  (input)  INTEGER array, dimension (N lg N) Contains a list of pointers which indicate where in GIVCOL a level's Givens rota-
tions are stored.  GIVPTR(i+1) - GIVPTR(i) indicates the number of Givens rotations.

GIVCOL (input) INTEGER array, dimension (2, N lg N) Each pair of numbers indicates a pair of columns to take place in a Givens rota-
tion.

GIVNUM  (input)  DOUBLE  PRECISION  array,  dimension  (2, N lg N) Each number indicates the S value to be used in the corresponding
Givens rotation.

Q      (input) DOUBLE PRECISION array, dimension (N**2)
Contains the square eigenblocks from previous levels, the starting positions for blocks are given by QPTR.

QPTR   (input) INTEGER array, dimension (N+2)
Contains a list of pointers which indicate where in Q an eigenblock is stored.  SQRT( QPTR(i+1) - QPTR(i) ) indicates  the  size	of
the block.

Z      (output) DOUBLE PRECISION array, dimension (N)
On output this vector contains the updating vector (the last row of the first sub-eigenvector matrix and the first row of the second
sub-eigenvector matrix).

ZTEMP  (workspace) DOUBLE PRECISION array, dimension (N)

INFO   (output) INTEGER
= 0:  successful exit.
< 0:  if INFO = -i, the i-th argument had an illegal value.

FURTHER DETAILS
Based on contributions by
Jeff Rutter, Computer Science Division, University of California
at Berkeley, USA

LAPACK version 3.0						   15 June 2000 							 DLAEDA(l)```
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