Ubuntu Manpage: trtri - trtri: triangular inverse

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NAME

       trtri - trtri: triangular inverse

SYNOPSIS

   Functions
       subroutine ctrtri (uplo, diag, n, a, lda, info)
           CTRTRI
       subroutine dtrtri (uplo, diag, n, a, lda, info)
           DTRTRI
       subroutine strtri (uplo, diag, n, a, lda, info)
           STRTRI
       subroutine ztrtri (uplo, diag, n, a, lda, info)
           ZTRTRI

Detailed Description

Function Documentation

subroutine ctrtri (character uplo, character diag, integer n, complex, dimension( lda, * ) a,
integer lda, integer info)
CTRTRI

Purpose:

CTRTRI computes the inverse of a complex upper or lower triangular
matrix A.

This is the Level 3 BLAS version of the algorithm.

Parameters
UPLO

UPLO is CHARACTER*1
= 'U': A is upper triangular;
= 'L': A is lower triangular.

DIAG

DIAG is CHARACTER*1
= 'N': A is non-unit triangular;
= 'U': A is unit triangular.

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

A is COMPLEX 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 = -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.

subroutine dtrtri (character uplo, character diag, integer n, double precision, dimension(
lda, * ) a, integer lda, integer info)
DTRTRI

Purpose:

DTRTRI computes the inverse of a real upper or lower triangular
matrix A.

This is the Level 3 BLAS version of the algorithm.

Parameters
UPLO

UPLO is CHARACTER*1
= 'U': A is upper triangular;
= 'L': A is lower triangular.

DIAG

DIAG is CHARACTER*1
= 'N': A is non-unit triangular;
= 'U': A is unit triangular.

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

A is 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

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

INFO

Author
Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

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

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
UPLO

UPLO is CHARACTER*1
= 'U': A is upper triangular;
= 'L': A is lower triangular.

DIAG

DIAG is CHARACTER*1
= 'N': A is non-unit triangular;
= 'U': A is unit triangular.

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

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

Author
Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

subroutine ztrtri (character uplo, character diag, integer n, complex*16, dimension( lda, * )
a, integer lda, integer info)
ZTRTRI

Purpose:

ZTRTRI computes the inverse of a complex upper or lower triangular
matrix A.

This is the Level 3 BLAS version of the algorithm.

Parameters
UPLO

UPLO is CHARACTER*1
= 'U': A is upper triangular;
= 'L': A is lower triangular.

DIAG

DIAG is CHARACTER*1
= 'N': A is non-unit triangular;
= 'U': A is unit triangular.

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

A is 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 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

Author
Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Author

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