Provided by: liblapack-doc_3.3.1-1_all #### NAME

```       LAPACK-3 - 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'

```

#### SYNOPSIS

```       SUBROUTINE SLARRC( JOBT, N, VL, VU, D, E, PIVMIN, EIGCNT, LCNT, RCNT, INFO )

CHARACTER      JOBT

INTEGER        EIGCNT, INFO, LCNT, N, RCNT

REAL           PIVMIN, VL, VU

REAL           D( * ), E( * )

```

#### 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'.

```

#### ARGUMENTS

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

N       (input) INTEGER
The order of the matrix. N > 0.

VL      (input) DOUBLE PRECISION
VU      (input) DOUBLE PRECISION
The lower and upper bounds for the eigenvalues.

D       (input) 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       (input) 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  (input) REAL
The minimum pivot in the Sturm sequence for T.

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

LCNT    (output) INTEGER
RCNT    (output) INTEGER
The left and right negcounts of the interval.

INFO    (output) INTEGER

```

#### FURTHERDETAILS

```        Based on contributions by
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

LAPACK auxiliary routine (version 3.2.2)   April 2011                            SLARRC(3lapack)
```