---
name: "dlattr.f"
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/dlattr.f"
---

# dlattr.f(3)

## NAME

TESTING/LIN/dlattr.f

## SYNOPSIS

### Functions/Subroutines

subroutine **dlattr** (imat, uplo, trans, diag, iseed, n, a, lda, b, work, info)\
 **DLATTR**

## Function/Subroutine Documentation

### subroutine dlattr (integer imat, character uplo, character trans, character diag, integer, dimension( 4 ) iseed, integer n, double precision, dimension( lda, \* ) a, integer lda, double precision, dimension( \* ) b, double precision, dimension( \* ) work, integer info)

**DLATTR**

**Purpose:**

```
!>
!> DLATTR generates a triangular test matrix.
!> IMAT and UPLO uniquely specify the properties of the test
!> matrix, which is returned in the array A.
!>
```

**Parameters**

*IMAT*

```
!>          IMAT is INTEGER
!>          An integer key describing which matrix to generate for this
!>          path.
!>
```

*UPLO*

```
!>          UPLO is CHARACTER*1
!>          Specifies whether the matrix A will be upper or lower
!>          triangular.
!>          = 'U':  Upper triangular
!>          = 'L':  Lower triangular
!>
```

*TRANS*

```
!>          TRANS is CHARACTER*1
!>          Specifies whether the matrix or its transpose will be used.
!>          = 'N':  No transpose
!>          = 'T':  Transpose
!>          = 'C':  Conjugate transpose (= Transpose)
!>
```

*DIAG*

```
!>          DIAG is CHARACTER*1
!>          Specifies whether or not the matrix A is unit triangular.
!>          = 'N':  Non-unit triangular
!>          = 'U':  Unit triangular
!>
```

*ISEED*

```
!>          ISEED is INTEGER array, dimension (4)
!>          The seed vector for the random number generator (used in
!>          DLATMS).  Modified on exit.
!>
```

*N*

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

*A*

```
!>          A is DOUBLE PRECISION array, dimension (LDA,N)
!>          The triangular matrix A.  If UPLO = 'U', the leading n by n
!>          upper triangular part of the array A contains the upper
!>          triangular matrix, and the strictly lower triangular part of
!>          A is not referenced.  If UPLO = 'L', the leading n by n lower
!>          triangular part of the array A contains the lower triangular
!>          matrix, and the strictly upper triangular part of A is not
!>          referenced.  If DIAG = 'U', the diagonal elements of A are
!>          set so that A(k,k) = k for 1 <= k <= n.
!>
```

*LDA*

```
!>          LDA is INTEGER
!>          The leading dimension of the array A.  LDA >= max(1,N).
!>
```

*B*

```
!>          B is DOUBLE PRECISION array, dimension (N)
!>          The right hand side vector, if IMAT > 10.
!>
```

*WORK*

```
!>          WORK is DOUBLE PRECISION array, dimension (3*N)
!>
```

*INFO*

```
!>          INFO is INTEGER
!>          = 0:  successful exit
!>          < 0: if INFO = -k, the k-th argument had an illegal value
!>
```

**Author**

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line **131** of file **dlattr.f**.

## Author

Generated automatically by Doxygen for LAPACK from the source code.