larrc - Man Page

larrc: step in stemr

Synopsis

Functions

subroutine dlarrc (jobt, n, vl, vu, d, e, pivmin, eigcnt, lcnt, rcnt, info)
DLARRC computes the number of eigenvalues of the symmetric tridiagonal matrix.
subroutine slarrc (jobt, n, vl, vu, d, e, pivmin, eigcnt, lcnt, rcnt, info)
SLARRC computes the number of eigenvalues of the symmetric tridiagonal matrix.

Function Documentation

subroutine dlarrc (character jobt, integer n, double precision vl, double precision vu, double precision, dimension( * ) d, double precision, dimension( * ) e, double precision pivmin, integer eigcnt, integer lcnt, integer rcnt, integer info)

DLARRC computes the number of eigenvalues of the symmetric tridiagonal matrix.

Purpose:

``` Find the number of eigenvalues of the symmetric tridiagonal matrix T
that are in the interval (VL,VU] if JOBT = 'T', and of L D L^T
if JOBT = 'L'.```
Parameters

JOBT

```          JOBT is CHARACTER*1
= 'T':  Compute Sturm count for matrix T.
= 'L':  Compute Sturm count for matrix L D L^T.```

N

```          N is INTEGER
The order of the matrix. N > 0.```

VL

```          VL is DOUBLE PRECISION
The lower bound for the eigenvalues.```

VU

```          VU is DOUBLE PRECISION
The upper bound for the eigenvalues.```

D

```          D is DOUBLE PRECISION array, dimension (N)
JOBT = 'T': The N diagonal elements of the tridiagonal matrix T.
JOBT = 'L': The N diagonal elements of the diagonal matrix D.```

E

```          E is DOUBLE PRECISION array, dimension (N)
JOBT = 'T': The N-1 offdiagonal elements of the matrix T.
JOBT = 'L': The N-1 offdiagonal elements of the matrix L.```

PIVMIN

```          PIVMIN is DOUBLE PRECISION
The minimum pivot in the Sturm sequence for T.```

EIGCNT

```          EIGCNT is INTEGER
The number of eigenvalues of the symmetric tridiagonal matrix T
that are in the interval (VL,VU]```

LCNT

`          LCNT is INTEGER`

RCNT

```          RCNT is INTEGER
The left and right negcounts of the interval.```

INFO

`          INFO is INTEGER`
Author

Univ. of Tennessee

Univ. of California Berkeley

NAG Ltd.

Contributors:

Beresford Parlett, University of California, Berkeley, USA
Jim Demmel, University of California, Berkeley, USA
Inderjit Dhillon, University of Texas, Austin, USA
Osni Marques, LBNL/NERSC, USA
Christof Voemel, University of California, Berkeley, USA

Definition at line 135 of file dlarrc.f.

subroutine slarrc (character jobt, integer n, real vl, real vu, real, dimension( * ) d, real, dimension( * ) e, real pivmin, integer eigcnt, integer lcnt, integer rcnt, integer info)

SLARRC computes the number of eigenvalues of the symmetric tridiagonal matrix.

Purpose:

``` Find the number of eigenvalues of the symmetric tridiagonal matrix T
that are in the interval (VL,VU] if JOBT = 'T', and of L D L^T
if JOBT = 'L'.```
Parameters

JOBT

```          JOBT is CHARACTER*1
= 'T':  Compute Sturm count for matrix T.
= 'L':  Compute Sturm count for matrix L D L^T.```

N

```          N is INTEGER
The order of the matrix. N > 0.```

VL

```          VL is REAL
The lower bound for the eigenvalues.```

VU

```          VU is REAL
The upper bound for the eigenvalues.```

D

```          D is REAL array, dimension (N)
JOBT = 'T': The N diagonal elements of the tridiagonal matrix T.
JOBT = 'L': The N diagonal elements of the diagonal matrix D.```

E

```          E is REAL array, dimension (N)
JOBT = 'T': The N-1 offdiagonal elements of the matrix T.
JOBT = 'L': The N-1 offdiagonal elements of the matrix L.```

PIVMIN

```          PIVMIN is REAL
The minimum pivot in the Sturm sequence for T.```

EIGCNT

```          EIGCNT is INTEGER
The number of eigenvalues of the symmetric tridiagonal matrix T
that are in the interval (VL,VU]```

LCNT

`          LCNT is INTEGER`

RCNT

```          RCNT is INTEGER
The left and right negcounts of the interval.```

INFO

`          INFO is INTEGER`
Author

Univ. of Tennessee

Univ. of California Berkeley

NAG Ltd.

Contributors:

Beresford Parlett, University of California, Berkeley, USA
Jim Demmel, University of California, Berkeley, USA
Inderjit Dhillon, University of Texas, Austin, USA
Osni Marques, LBNL/NERSC, USA
Christof Voemel, University of California, Berkeley, USA

Definition at line 135 of file slarrc.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Info

Tue Nov 28 2023 12:08:43 Version 3.12.0 LAPACK