# dtrtri.f man page

dtrtri.f

## Synopsis

### Functions/Subroutines

subroutine dtrtri (UPLO, DIAG, N, A, LDA, INFO)
DTRTRI

## Function/Subroutine Documentation

### subroutine dtrtri (character UPLO, character DIAG, integer N, double precision, dimension( lda, * ) A, integer LDA, integer INFO)

DTRTRI

Purpose:

``` DTRTRI computes the inverse of a real upper or lower triangular
matrix A.

This is the Level 3 BLAS version of the algorithm.```
Parameters:

UPLO

```          UPLO is CHARACTER*1
= 'U':  A is upper triangular;
= 'L':  A is lower triangular.```

DIAG

```          DIAG is CHARACTER*1
= 'N':  A is non-unit triangular;
= 'U':  A is 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 = -i, the i-th argument had an illegal value
> 0: if INFO = i, A(i,i) is exactly zero.  The triangular
matrix is singular and its inverse can not be computed.```
Author:

Univ. of Tennessee

Univ. of California Berkeley

NAG Ltd.

Date:

December 2016

Definition at line 111 of file dtrtri.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page dtrtri(3) is an alias of dtrtri.f(3).

Tue Nov 14 2017 Version 3.8.0 LAPACK