---
name: "dlattb.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/dlattb.f"
---

# dlattb.f(3)

## NAME

TESTING/LIN/dlattb.f

## SYNOPSIS

### Functions/Subroutines

subroutine **dlattb** (imat, uplo, trans, diag, iseed, n, kd, ab, ldab, b, work, info)\
 **DLATTB**

## Function/Subroutine Documentation

### subroutine dlattb (integer imat, character uplo, character trans, character diag, integer, dimension( 4 ) iseed, integer n, integer kd, double precision, dimension( ldab, \* ) ab, integer ldab, double precision, dimension( \* ) b, double precision, dimension( \* ) work, integer info)

**DLATTB**

**Purpose:**

```
!>
!> DLATTB generates a triangular test matrix in 2-dimensional storage.
!> 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.
!>
```

*KD*

```
!>          KD is INTEGER
!>          The number of superdiagonals or subdiagonals of the banded
!>          triangular matrix A.  KD >= 0.
!>
```

*AB*

```
!>          AB is DOUBLE PRECISION array, dimension (LDAB,N)
!>          The upper or lower triangular banded matrix A, stored in the
!>          first KD+1 rows of AB.  Let j be a column of A, 1<=j<=n.
!>          If UPLO = 'U', AB(kd+1+i-j,j) = A(i,j) for max(1,j-kd)<=i<=j.
!>          If UPLO = 'L', AB(1+i-j,j)    = A(i,j) for j<=i<=min(n,j+kd).
!>
```

*LDAB*

```
!>          LDAB is INTEGER
!>          The leading dimension of the array AB.  LDAB >= KD+1.
!>
```

*B*

```
!>          B is DOUBLE PRECISION array, dimension (N)
!>
```

*WORK*

```
!>          WORK is DOUBLE PRECISION array, dimension (2*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 **133** of file **dlattb.f**.

## Author

Generated automatically by Doxygen for LAPACK from the source code.