TESTING/LIN/dtrt06.f(3)

NAME
TESTING/LIN/dtrt06.f

SYNOPSIS

  Functions/Subroutines
subroutine dtrt06 (rcond, rcondc, uplo, diag, n, a, lda, work, rat)
DTRT06

Function/Subroutine Documentation

  subroutine dtrt06 (double precision rcond, double precision rcondc, character uplo, character diag, integer n, double precision, dimension( lda, * ) a, integer lda, double precision, dimension( * ) work, double precision rat)

DTRT06

Purpose:

     DTRT06 computes a test ratio comparing RCOND (the reciprocal
     condition number of a triangular matrix A) and RCONDC, the estimate
     computed by DTRCON.  Information about the triangular matrix A is
     used if one estimate is zero and the other is non-zero to decide if
     underflow in the estimate is justified.

Parameters
    RCOND

              RCOND is DOUBLE PRECISION
              The estimate of the reciprocal condition number obtained by
              forming the explicit inverse of the matrix A and computing
              RCOND = 1/( norm(A) * norm(inv(A)) ).

    RCONDC

              RCONDC is DOUBLE PRECISION
              The estimate of the reciprocal condition number computed by
              DTRCON.

    UPLO

              UPLO is CHARACTER
              Specifies whether the matrix A is upper or lower triangular.
              = 'U':  Upper triangular
              = 'L':  Lower triangular

    DIAG

              DIAG is CHARACTER
              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).

    WORK

              WORK is DOUBLE PRECISION array, dimension (N)

    RAT

              RAT is DOUBLE PRECISION
              The test ratio.  If both RCOND and RCONDC are nonzero,
                 RAT = MAX( RCOND, RCONDC )/MIN( RCOND, RCONDC ) - 1.
              If RAT = 0, the two estimates are exactly the same.

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 119 of file dtrt06.f.

Author

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