Developer Reference

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

?larrc

Computes the number of eigenvalues of the symmetric tridiagonal matrix.

Syntax

call slarrc
(
jobt
,
n
,
vl
,
vu
,
d
,
e
,
pivmin
,
eigcnt
,
lcnt
,
rcnt
,
info
)
call dlarrc
(
jobt
,
n
,
vl
,
vu
,
d
,
e
,
pivmin
,
eigcnt
,
lcnt
,
rcnt
,
info
)
Include Files
  • mkl.fi
Description
The routine finds the number of eigenvalues of the symmetric tridiagonal matrix
T
or of its factorization
L
*
D
*
L
T
in the specified interval.
Input Parameters
jobt
CHARACTER*1
.
= 'T'
: computes Sturm count for matrix
T
.
= 'L'
: computes Sturm count for matrix
L
*
D
*
L
T
.
n
INTEGER
.
The order of the matrix. (
n
>
1
).
vl
,
vu
REAL
for
slarrc
DOUBLE PRECISION
for
dlarrc
The lower and upper bounds for the eigenvalues.
d
REAL
for
slarrc
DOUBLE PRECISION
for
dlarrc
Array,
DIMENSION
(
n
).
If
jobt
= 'T'
: contains the
n
diagonal elements of the tridiagonal matrix
T
.
If
jobt
= 'L'
: contains the
n
diagonal elements of the diagonal matrix
D
.
e
REAL
for
slarrc
DOUBLE PRECISION
for
dlarrc
Array,
DIMENSION
(
n
).
If
jobt
= 'T'
: contains the
(
n
-1)
offdiagonal elements of the matrix
T
.
If
jobt
= 'L'
: contains the
(
n
-1)
offdiagonal elements of the matrix
L
.
pivmin
REAL
for
slarrc
DOUBLE PRECISION
for
dlarrc
The minimum pivot in the Sturm sequence for the matrix
T
.
Output Parameters
eigcnt
INTEGER
.
The number of eigenvalues of the symmetric tridiagonal matrix
T
that are in the half-open interval
(
vl
,
vu
]
.
lcnt
,
rcnt
INTEGER
.
The left and right negcounts of the interval.
info
INTEGER
.
Now it is not used and always is set to 0.

Product and Performance Information

1

Intel's compilers may or may not optimize to the same degree for non-Intel microprocessors for optimizations that are not unique to Intel microprocessors. These optimizations include SSE2, SSE3, and SSSE3 instruction sets and other optimizations. Intel does not guarantee the availability, functionality, or effectiveness of any optimization on microprocessors not manufactured by Intel. Microprocessor-dependent optimizations in this product are intended for use with Intel microprocessors. Certain optimizations not specific to Intel microarchitecture are reserved for Intel microprocessors. Please refer to the applicable product User and Reference Guides for more information regarding the specific instruction sets covered by this notice.

Notice revision #20110804