strtri()

subroutine strtri	(	character	uplo,
		character	diag,
		integer	n,
		real, dimension( lda, * )	a,
		integer	lda,
		integer	info )

STRTRI

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Purpose:

!>
!> STRTRI computes the inverse of a real upper or lower triangular
!> matrix A.
!>
!> This is the Level 3 BLAS version of the algorithm.
!> 

Parameters

[in]	UPLO	!> UPLO is CHARACTER*1 !> = 'U': A is upper triangular; !> = 'L': A is lower triangular. !>
[in]	DIAG	!> DIAG is CHARACTER*1 !> = 'N': A is non-unit triangular; !> = 'U': A is unit triangular. !>
[in]	N	!> N is INTEGER !> The order of the matrix A. N >= 0. !>
[in,out]	A	!> A is REAL 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. !>
[in]	LDA	!> LDA is INTEGER !> The leading dimension of the array A. LDA >= max(1,N). !>
[out]	INFO	!> INFO is 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. !>

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.