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

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