trtri(3)

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

              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 = -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.

Definition at line 108 of file ctrtri.f.

  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

              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 = -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.

Definition at line 108 of file dtrtri.f.

  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

              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 = -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.

Definition at line 108 of file strtri.f.

  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

              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 = -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.

Definition at line 108 of file ztrtri.f.

Author

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