# dlarrc.f man page

dlarrc.f —

## Synopsis

### Functions/Subroutines

subroutinedlarrc(JOBT, N, VL, VU, D, E, PIVMIN, EIGCNT, LCNT, RCNT, INFO)DLARRCcomputes the number of eigenvalues of the symmetric tridiagonal matrix.

## Function/Subroutine Documentation

### subroutine dlarrc (characterJOBT, integerN, double precisionVL, double precisionVU, double precision, dimension( * )D, double precision, dimension( * )E, double precisionPIVMIN, integerEIGCNT, integerLCNT, integerRCNT, integerINFO)

**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`

*VU*

```
VU is DOUBLE PRECISION
The lower and upper bounds 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

Univ. of Colorado Denver

NAG Ltd.

**Date:**

September 2012

**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 136 of file dlarrc.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

dlarrc(3) is an alias of dlarrc.f(3).