---
name: "sstev"
section: "3"
platform: "linux"
package: "lapack-doc"
version: "3.12.1-2"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/sstev.f"
---

# sstev(3)

Part of [sstev.f(3)](/sstev.f/3.md).

## NAME

SRC/sstev.f

## SYNOPSIS

### Functions/Subroutines

subroutine **sstev** (jobz, n, d, e, z, ldz, work, info)\
  **SSTEV computes the eigenvalues and, optionally, the left and/or right eigenvectors for OTHER matrices**

## Function/Subroutine Documentation

### subroutine sstev (character jobz, integer n, real, dimension( \* ) d, real, dimension( \* ) e, real, dimension( ldz, \* ) z, integer ldz, real, dimension( \* ) work, integer info)

 **SSTEV computes the eigenvalues and, optionally, the left and/or right eigenvectors for OTHER matrices**

**Purpose:**

```
!>
!> SSTEV computes all eigenvalues and, optionally, eigenvectors of a
!> real symmetric tridiagonal matrix A.
!>
```

**Parameters**

*JOBZ*

```
!>          JOBZ is CHARACTER*1
!>          = 'N':  Compute eigenvalues only;
!>          = 'V':  Compute eigenvalues and eigenvectors.
!>
```

*N*

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

*D*

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

*E*

```
!>          E is REAL array, dimension (N-1)
!>          On entry, the (n-1) subdiagonal elements of the tridiagonal
!>          matrix A, stored in elements 1 to N-1 of E.
!>          On exit, the contents of E are destroyed.
!>
```

*Z*

```
!>          Z is REAL array, dimension (LDZ, N)
!>          If JOBZ = 'V', then if INFO = 0, Z contains the orthonormal
!>          eigenvectors of the matrix A, with the i-th column of Z
!>          holding the eigenvector associated with D(i).
!>          If JOBZ = 'N', then Z is not referenced.
!>
```

*LDZ*

```
!>          LDZ is INTEGER
!>          The leading dimension of the array Z.  LDZ >= 1, and if
!>          JOBZ = 'V', LDZ >= max(1,N).
!>
```

*WORK*

```
!>          WORK is REAL array, dimension (max(1,2*N-2))
!>          If JOBZ = 'N', WORK is not referenced.
!>
```

*INFO*

```
!>          INFO is INTEGER
!>          = 0:  successful exit
!>          < 0:  if INFO = -i, the i-th argument had an illegal value
!>          > 0:  if INFO = i, the algorithm failed to converge; i
!>                off-diagonal elements of E did not converge to zero.
!>
```

**Author**

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line **115** of file **sstev.f**.

## Author

Generated automatically by Doxygen for LAPACK from the source code.