# slarrc.f - Man Page

SRC/slarrc.f

## Synopsis

### Functions/Subroutines

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/Subroutine Documentation

### 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.

## Referenced By

The man page slarrc(3) is an alias of slarrc.f(3).

Tue Nov 28 2023 12:08:42 Version 3.12.0 LAPACK