# dsterf.f man page

dsterf.f —

## Synopsis

### Functions/Subroutines

subroutinedsterf(N, D, E, INFO)DSTERF

## Function/Subroutine Documentation

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

**DSTERF**

**Purpose:**

```
DSTERF computes all eigenvalues of a symmetric tridiagonal matrix
using the Pal-Walker-Kahan variant of the QL or QR algorithm.
```

**Parameters:**

*N*

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

*D*

```
D is DOUBLE PRECISION array, dimension (N)
On entry, the n diagonal elements of the tridiagonal matrix.
On exit, if INFO = 0, the eigenvalues in ascending order.
```

*E*

```
E is DOUBLE PRECISION array, dimension (N-1)
On entry, the (n-1) subdiagonal elements of the tridiagonal
matrix.
On exit, E has been destroyed.
```

*INFO*

```
INFO is INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
> 0: the algorithm failed to find all of the eigenvalues in
a total of 30*N iterations; if INFO = i, then i
elements of E have not converged to zero.
```

**Author:**

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

**Date:**

November 2011

Definition at line 87 of file dsterf.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

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

Sat Nov 16 2013 Version 3.4.2 LAPACK