NAME
ZTRTRI - computes the inverse of a complex upper or lower triangular matrix A
SYNOPSIS
- SUBROUTINE ZTRTRI(
-
UPLO, DIAG, N, A, LDA, INFO )
- CHARACTER
-
DIAG, UPLO
- INTEGER
-
INFO, LDA, N
- COMPLEX*16
-
A( LDA, * )
PURPOSE
ZTRTRI computes the inverse of a complex upper or lower triangular matrix A. This is the Level 3 BLAS version of the algorithm.
ARGUMENTS
- UPLO (input) CHARACTER*1
-
= 'U': A is upper triangular;
= 'L': A is lower triangular.
- DIAG (input) CHARACTER*1
-
= 'N': A is non-unit triangular;
= 'U': A is unit triangular.
- N (input) INTEGER
-
The order of the matrix A. N >= 0.
- A (input/output) 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 (input) INTEGER
-
The leading dimension of the array A. LDA >= max(1,N).
- INFO (output) 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.