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

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

    A

    !>          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.

  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

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

    A

    !>          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.

  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

    !>          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.

  subroutine ztrti2 (character uplo, character diag, integer n, complex*16, 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

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

    A

    !>          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.

Author

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