# ztrtri (3) - Linux Man Pages

ztrtri.f -

## SYNOPSIS

### Functions/Subroutines

subroutine ztrtri (UPLO, DIAG, N, A, LDA, INFO)
ZTRTRI

## Function/Subroutine Documentation

### subroutine ztrtri (characterUPLO, characterDIAG, integerN, complex*16, dimension( lda, * )A, integerLDA, integerINFO)

ZTRTRI

Purpose:

``` ZTRTRI computes the inverse of a complex 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 COMPLEX*16 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