trti2(3)

Library Functions Manual

trti2(3)

NAME

trti2 - trti2: triangular inverse, level 2

SYNOPSIS

Functions

subroutine ctrti2 (uplo, diag, n, a, lda, info)
CTRTI2 computes the inverse of a triangular matrix (unblocked algorithm). subroutine dtrti2 (uplo, diag, n, a, lda, info)
DTRTI2 computes the inverse of a triangular matrix (unblocked algorithm). subroutine strti2 (uplo, diag, n, a, lda, info)
STRTI2 computes the inverse of a triangular matrix (unblocked algorithm). subroutine ztrti2 (uplo, diag, n, a, lda, info)
ZTRTI2 computes the inverse of a triangular matrix (unblocked algorithm).

Detailed Description

Function Documentation

subroutine ctrti2 (character uplo, character diag, integer n, complex, dimension( lda, * ) a, integer lda, integer info)

CTRTI2 computes the inverse of a triangular matrix (unblocked algorithm).

Purpose:

 CTRTI2 computes the inverse of a complex 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 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 = -k, the k-th argument had an illegal value

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 109 of file ctrti2.f.

subroutine dtrti2 (character uplo, character diag, integer n, double precision, dimension( lda, * ) a, integer lda, integer info)

DTRTI2 computes the inverse of a triangular matrix (unblocked algorithm).

Purpose:

 DTRTI2 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 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

          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.

Definition at line 109 of file dtrti2.f.

subroutine strti2 (character uplo, character diag, integer n, real, dimension( lda, * ) a, integer lda, integer info)

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

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 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

          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.

Definition at line 109 of file strti2.f.

subroutine ztrti2 (character uplo, character diag, integer n, complex16, dimension( lda, ) a, integer lda, integer info)

ZTRTI2 computes the inverse of a triangular matrix (unblocked algorithm).

Purpose:

 ZTRTI2 computes the inverse of a complex 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 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

          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.

Definition at line 109 of file ztrti2.f.

Author

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