ztrti2(3)

NAME

ZTRTI2 - compute the inverse of a complex upper or lower

triangular matrix

SYNOPSIS

SUBROUTINE ZTRTI2( UPLO, DIAG, N, A, LDA, INFO )
    CHARACTER      DIAG, UPLO
    INTEGER        INFO, LDA, N
    COMPLEX*16     A( LDA, * )

PURPOSE

ZTRTI2 computes the inverse of a complex upper or lower

triangular matrix. This is the Level 2 BLAS version of the algo

rithm.

ARGUMENTS

UPLO (input) CHARACTER*1

Specifies whether the matrix A is upper or lower

triangular. = 'U': Upper triangular
= 'L': Lower triangular

DIAG (input) CHARACTER*1

Specifies whether or not the matrix A is unit tri

angular. = 'N': Non-unit triangular
= 'U': 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 triangu

lar 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 = -k, the k-th argument had an ille

gal value

LAPACK version 3.0 15 June 2000

ZTRTI2(3)