Developer Reference

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

?lasq4

Computes an approximation to the smallest eigenvalue using values of d from the previous transform. Used by
?bdsqr
.

Syntax

call slasq4
(
i0
,
n0
,
z
,
pp
,
n0in
,
dmin
,
dmin1
,
dmin2
,
dn
,
dn1
,
dn2
,
tau
,
ttype
,
g
)
call dlasq4
(
i0
,
n0
,
z
,
pp
,
n0in
,
dmin
,
dmin1
,
dmin2
,
dn
,
dn1
,
dn2
,
tau
,
ttype
,
g
)
Include Files
  • mkl.fi
Description
The routine computes an approximation
tau
to the smallest eigenvalue using values of d from the previous transform.
Input Parameters
i0
INTEGER
. First index.
n0
INTEGER
. Last index.
z
REAL
for
slasq4
DOUBLE PRECISION
for
dlasq4
.
Array,
DIMENSION
(4
n
).
z
holds the
qd
array.
pp
INTEGER
.
pp
=0
for ping,
pp
=1
for pong.
n0in
INTEGER
. The value of
n0
at start of
eigtest
.
dmin
REAL
for
slasq4
DOUBLE PRECISION
for
dlasq4
.
Minimum value of
d
.
dmin1
REAL
for
slasq4
DOUBLE PRECISION
for
dlasq4
.
Minimum value of
d
, excluding
d
(
n0
).
dmin2
REAL
for
slasq4
DOUBLE PRECISION
for
dlasq4
.
Minimum value of
d
, excluding
d
(
n0
) and
d
(
n0
-1).
dn
REAL
for
slasq4
DOUBLE PRECISION
for
dlasq4
. Contains
d
(
n
).
dn1
REAL
for
slasq4
DOUBLE PRECISION
for
dlasq4
. Contains
d
(
n
-1).
dn2
REAL
for
slasq4
DOUBLE PRECISION
for
dlasq4
. Contains
d
(
n
-2).
g
REAL
for
slasq4
DOUBLE PRECISION
for
dlasq4
.
A scalar passed as an argument in order to save its value between calls to
?lasq4
.
Output Parameters
tau
REAL
for
slasq4
DOUBLE PRECISION
for
dlasq4
.
Shift.
ttype
INTEGER
. Shift type.
g
REAL
for
slasq4
DOUBLE PRECISION
for
dlasq4
.
A scalar passed as an argument in order to save its value between calls to
?lasq4
.