# dtrti2.f man page

dtrti2.f —

## Synopsis

### Functions/Subroutines

subroutinedtrti2(UPLO, DIAG, N, A, LDA, INFO)DTRTI2computes the inverse of a triangular matrix (unblocked algorithm).

## Function/Subroutine Documentation

### subroutine dtrti2 (characterUPLO, characterDIAG, integerN, double precision, dimension( lda, * )A, integerLDA, integerINFO)

**DTRTI2** computes the inverse of a triangular matrix (unblocked algorithm).

**Purpose:**

```
DTRTI2 computes the inverse of a real upper or lower triangular
matrix.
This is the Level 2 BLAS version of the algorithm.
```

**Parameters:**

*UPLO*

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

*DIAG*

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

*N*

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

*A*

```
A is DOUBLE PRECISION array, dimension (LDA,N)
On entry, 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 also not referenced and are
assumed to be 1.
On exit, the (triangular) inverse of the original matrix, in
the same storage format.
```

*LDA*

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

**Date:**

September 2012

Definition at line 111 of file dtrti2.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

dtrti2(3) is an alias of dtrti2.f(3).

Sat Nov 16 2013 Version 3.4.2 LAPACK