strti2.f −

**Functions/Subroutines**

subroutine **strti2** (UPLO, DIAG, N, A, LDA, INFO)

STRTI2*computes the inverse of a triangular matrix (unblocked algorithm).*

* subroutine strti2 (characterUPLO, characterDIAG, integerN, real, dimension( lda, * )A, integerLDA, integerINFO)* computes the inverse of a triangular matrix (unblocked algorithm).

STRTI2

**Purpose:**

STRTI2 computes the inverse of a real upper or lower triangular

matrix.

This is the Level 2 BLAS version of the algorithm.

**Parameters:**

*UPLO*

UPLO is CHARACTER*1

Specifies whether the matrix A is upper or lower triangular.

= ’U’: Upper triangular

= ’L’: Lower triangular

*DIAG*

DIAG is CHARACTER*1

Specifies whether or not the matrix A is unit triangular.

= ’N’: Non-unit triangular

= ’U’: Unit triangular

*N*

N is INTEGER

The order of the matrix A. N >= 0.

*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.

*LDA*

LDA is INTEGER

The leading dimension of the array A. LDA >= max(1,N).

*INFO*

INFO is INTEGER

= 0: successful exit

< 0: if INFO = -k, the k-th argument had an illegal value

**Author:**

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

**Date:**

September 2012

Definition at line 111 of file strti2.f.

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