---
name: "zlatsy"
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/zlatsy.f"
---

# zlatsy(3)

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

## NAME

TESTING/LIN/zlatsy.f

## SYNOPSIS

### Functions/Subroutines

subroutine **zlatsy** (uplo, n, x, ldx, iseed)\
 **ZLATSY**

## Function/Subroutine Documentation

### subroutine zlatsy (character uplo, integer n, complex\*16, dimension( ldx, \* ) x, integer ldx, integer, dimension( \* ) iseed)

**ZLATSY**

**Purpose:**

```
!>
!> ZLATSY generates a special test matrix for the complex symmetric
!> (indefinite) factorization.  The pivot blocks of the generated matrix
!> will be in the following order:
!>    2x2 pivot block, non diagonalizable
!>    1x1 pivot block
!>    2x2 pivot block, diagonalizable
!>    (cycle repeats)
!> A row interchange is required for each non-diagonalizable 2x2 block.
!>
```

**Parameters**

*UPLO*

```
!>          UPLO is CHARACTER
!>          Specifies whether the generated matrix is to be upper or
!>          lower triangular.
!>          = 'U':  Upper triangular
!>          = 'L':  Lower triangular
!>
```

*N*

```
!>          N is INTEGER
!>          The dimension of the matrix to be generated.
!>
```

*X*

```
!>          X is COMPLEX*16 array, dimension (LDX,N)
!>          The generated matrix, consisting of 3x3 and 2x2 diagonal
!>          blocks which result in the pivot sequence given above.
!>          The matrix outside of these diagonal blocks is zero.
!>
```

*LDX*

```
!>          LDX is INTEGER
!>          The leading dimension of the array X.
!>
```

*ISEED*

```
!>          ISEED is INTEGER array, dimension (4)
!>          On entry, the seed for the random number generator.  The last
!>          of the four integers must be odd.  (modified on exit)
!>
```

**Author**

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line **88** of file **zlatsy.f**.

## Author

Generated automatically by Doxygen for LAPACK from the source code.