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 algorithm.


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  triangular  matrix,  and the strictly upper
               triangular part of A is not referenced.  If DIAG =
               'U',  the diagonal elements of A are also not ref­
               erenced 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

               gal value


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