TESTING/LIN/dtpt06.f(3)

NAME
TESTING/LIN/dtpt06.f

SYNOPSIS

  Functions/Subroutines
subroutine dtpt06 (rcond, rcondc, uplo, diag, n, ap, work, rat)
DTPT06

Function/Subroutine Documentation

  subroutine dtpt06 (double precision rcond, double precision rcondc, character uplo, character diag, integer n, double precision, dimension( * ) ap, double precision, dimension( * ) work, double precision rat)

DTPT06

Purpose:

    !>
    !> DTPT06 computes a test ratio comparing RCOND (the reciprocal
    !> condition number of a triangular matrix A) and RCONDC, the estimate
    !> computed by DTPCON.  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
    !>          DTPCON.
    !>

    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.
    !>

    AP

    !>          AP is DOUBLE PRECISION array, dimension (N*(N+1)/2)
    !>          The upper or lower triangular matrix A, packed columnwise in
    !>          a linear array.  The j-th column of A is stored in the array
    !>          AP as follows:
    !>          if UPLO = 'U', AP((j-1)*j/2 + i) = A(i,j) for 1<=i<=j;
    !>          if UPLO = 'L',
    !>             AP((j-1)*(n-j) + j*(j+1)/2 + i-j) = A(i,j) for j<=i<=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 110 of file dtpt06.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.