TESTING/LIN/dtrt01.f(3)

NAME
TESTING/LIN/dtrt01.f

SYNOPSIS

  Functions/Subroutines
subroutine dtrt01 (uplo, diag, n, a, lda, ainv, ldainv, rcond, work, resid)
DTRT01

Function/Subroutine Documentation

  subroutine dtrt01 (character uplo, character diag, integer n, double precision, dimension( lda, * ) a, integer lda, double precision, dimension( ldainv, * ) ainv, integer ldainv, double precision rcond, double precision, dimension( * ) work, double precision resid)

DTRT01

Purpose:

     DTRT01 computes the residual for a triangular matrix A times its
     inverse:
        RESID = norm( A*AINV - I ) / ( N * norm(A) * norm(AINV) * EPS ),
     where EPS is the machine epsilon.

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)
              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.

    LDA

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

    AINV

              AINV is DOUBLE PRECISION array, dimension (LDAINV,N)
              On entry, the (triangular) inverse of the matrix A, in the
              same storage format as A.
              On exit, the contents of AINV are destroyed.

    LDAINV

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

    RCOND

              RCOND is DOUBLE PRECISION
              The reciprocal condition number of A, computed as
              1/(norm(A) * norm(AINV)).

    WORK

              WORK is DOUBLE PRECISION array, dimension (N)

    RESID

              RESID is DOUBLE PRECISION
              norm(A*AINV - I) / ( N * norm(A) * norm(AINV) * EPS )

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 122 of file dtrt01.f.

Author

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