Developer Reference

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

?tgsna

Estimates reciprocal condition numbers for specified eigenvalues and/or eigenvectors of a pair of matrices in generalized real Schur canonical form.

Syntax

call stgsna
(
job
,
howmny
,
select
,
n
,
a
,
lda
,
b
,
ldb
,
vl
,
ldvl
,
vr
,
ldvr
,
s
,
dif
,
mm
,
m
,
work
,
lwork
,
iwork
,
info
)
call dtgsna
(
job
,
howmny
,
select
,
n
,
a
,
lda
,
b
,
ldb
,
vl
,
ldvl
,
vr
,
ldvr
,
s
,
dif
,
mm
,
m
,
work
,
lwork
,
iwork
,
info
)
call ctgsna
(
job
,
howmny
,
select
,
n
,
a
,
lda
,
b
,
ldb
,
vl
,
ldvl
,
vr
,
ldvr
,
s
,
dif
,
mm
,
m
,
work
,
lwork
,
iwork
,
info
)
call ztgsna
(
job
,
howmny
,
select
,
n
,
a
,
lda
,
b
,
ldb
,
vl
,
ldvl
,
vr
,
ldvr
,
s
,
dif
,
mm
,
m
,
work
,
lwork
,
iwork
,
info
)
call tgsna
(
a
,
b
[
,
s
]
[
,
dif
]
[
,
vl
]
[
,
vr
]
[
,
select
]
[
,
m
]
[
,
info
]
)
Include Files
  • mkl.fi
    ,
    lapack.f90
Description
The real flavors
stgsna
/
dtgsna
of this routine estimate reciprocal condition numbers for specified eigenvalues and/or eigenvectors of a matrix pair (
A
,
B
) in generalized real Schur canonical form (or of any matrix pair (
Q
*A*
Z
T
,
Q*
B*
Z
T
) with orthogonal matrices
Q
and
Z
.
(
A
,
B
) must be in generalized real Schur form (as returned by gges/