Developer Reference

  • 2020.2
  • 07/15/2020
  • Public Content
Contents

?laed8

Used by
?stedc
. Merges eigenvalues and deflates secular equation. Used when the original matrix is dense.

Syntax

call slaed8
(
icompq
,
k
,
n
,
qsiz
,
d
,
q
,
ldq
,
indxq
,
rho
,
cutpnt
,
z
,
dlamda
,
q2
,
ldq2
,
w
,
perm
,
givptr
,
givcol
,
givnum
,
indxp
,
indx
,
info
)
call dlaed8
(
icompq
,
k
,
n
,
qsiz
,
d
,
q
,
ldq
,
indxq
,
rho
,
cutpnt
,
z
,
dlamda
,
q2
,
ldq2
,
w
,
perm
,
givptr
,
givcol
,
givnum
,
indxp
,
indx
,
info
)
call claed8
(
k
,
n
,
qsiz
,
q
,
ldq
,
d
,
rho
,
cutpnt
,
z
,
dlamda
,
q2
,
ldq2
,
w
,
indxp
,
indx
,
indxq
,
perm
,
givptr
,
givcol
,
givnum
,
info
)
call zlaed8
(
k
,
n
,
qsiz
,
q
,
ldq
,
d
,
rho
,
cutpnt
,
z
,
dlamda
,
q2
,
ldq2
,
w
,
indxp
,
indx
,
indxq
,
perm
,
givptr
,
givcol
,
givnum
,
info
)
Include Files
  • mkl.fi
Description
The routine merges the two sets of eigenvalues together into a single sorted set. Then it tries to deflate the size of the problem. There are two ways in which deflation can occur: when two or more eigenvalues are close together or if there is a tiny element in the
z
vector. For each such occurrence the order of the related secular equation problem is reduced by one.
Input Parameters
icompq
INTEGER
. Used with real flavors only.
If
icompq
= 0
, compute eigenvalues only.
If
icompq
= 1
, compute eigenvectors of original dense symmetric matrix also.
On entry, the array
q
must contain the orthogonal matrix used to reduce the original matrix to tridiagonal form.
n
INTEGER
. The dimension of the symmetric tridiagonal matrix (
n
0
).