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SRC/lapack_64_obj/slaeda.f(3) Library Functions Manual SRC/lapack_64_obj/slaeda.f(3)

NAME

SRC/lapack_64_obj/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 (integer n, integer tlvls, integer curlvl, integer curpbm, 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, integer 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.

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.

Contributors:

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

Definition at line 165 of file slaeda.f.

Author

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