DTRTI2(3)
computes the inverse of a real upper or lower triangular matrix
SYNOPSIS
 SUBROUTINE DTRTI2(

UPLO, DIAG, N, A, LDA, INFO )

CHARACTER
DIAG, UPLO

INTEGER
INFO, LDA, N

DOUBLE
PRECISION A( LDA, * )
PURPOSE
DTRTI2 computes the inverse of a real 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 triangular.
= 'N': Nonunit 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 kth argument had an illegal value