# dlarrr.f man page

dlarrr.f —

## Synopsis

### Functions/Subroutines

subroutinedlarrr(N, D, E, INFO)DLARRRperforms tests to decide whether the symmetric tridiagonal matrix T warrants expensive computations which guarantee high relative accuracy in the eigenvalues.

## Function/Subroutine Documentation

### subroutine dlarrr (integerN, double precision, dimension( * )D, double precision, dimension( * )E, integerINFO)

**DLARRR** performs tests to decide whether the symmetric tridiagonal matrix T warrants expensive computations which guarantee high relative accuracy in the eigenvalues.

**Purpose:**

```
Perform tests to decide whether the symmetric tridiagonal matrix T
warrants expensive computations which guarantee high relative accuracy
in the eigenvalues.
```

**Parameters:**

*N*

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

*D*

```
D is DOUBLE PRECISION array, dimension (N)
The N diagonal elements of the tridiagonal matrix T.
```

*E*

```
E is DOUBLE PRECISION array, dimension (N)
On entry, the first (N-1) entries contain the subdiagonal
elements of the tridiagonal matrix T; E(N) is set to ZERO.
```

*INFO*

```
INFO is INTEGER
INFO = 0(default) : the matrix warrants computations preserving
relative accuracy.
INFO = 1 : the matrix warrants computations guaranteeing
only absolute accuracy.
```

**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 95 of file dlarrr.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

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