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dlaeda-f(3)

dlaeda.f –

Synopsis

Functions/Subroutines

subroutine dlaeda (N, TLVLS, CURLVL, CURPBM, PRMPTR, PERM, GIVPTR, GIVCOL, GIVNUM, Q, QPTR, Z, ZTEMP, INFO)
DLAEDA 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 dlaeda (integerN, integerTLVLS, integerCURLVL, integerCURPBM, integer, dimension( * )PRMPTR, integer, dimension( * )PERM, integer, dimension( * )GIVPTR, integer, dimension( 2, * )GIVCOL, double precision, dimension( 2, * )GIVNUM, double precision, dimension( * )Q, integer, dimension( * )QPTR, double precision, dimension( * )Z, double precision, dimension( * )ZTEMP, integerINFO)

DLAEDA used by sstedc. Computes the Z vector determining the rank-one modification of the diagonal matrix. Used when the original matrix is dense.

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.

 

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

Q

 Q is DOUBLE PRECISION 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 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

 ZTEMP is DOUBLE PRECISION 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 dlaeda.f.

Author

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