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NAME
     dtrti2 - compute the inverse of a real upper or  lower  tri-
     angular matrix

SYNOPSIS
     SUBROUTINE DTRTI2( UPLO, DIAG, N, A, LDA, INFO )

     CHARACTER DIAG, UPLO

     INTEGER INFO, LDA, N

     DOUBLE PRECISION A( LDA, * )



     #include <sunperf.h>

     void dtrti2(char uplo, char diag, int  n,  double  *da,  int
               lda, int *info) ;

PURPOSE
     DTRTI2 computes the inverse of a real upper  or  lower  tri-
     angular 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) 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       (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

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