TESTING/EIG/dhst01.f(3)

NAME
TESTING/EIG/dhst01.f

SYNOPSIS

  Functions/Subroutines
subroutine dhst01 (n, ilo, ihi, a, lda, h, ldh, q, ldq, work, lwork, result)
DHST01

Function/Subroutine Documentation

  subroutine dhst01 (integer n, integer ilo, integer ihi, double precision, dimension( lda, * ) a, integer lda, double precision, dimension( ldh, * ) h, integer ldh, double precision, dimension( ldq, * ) q, integer ldq, double precision, dimension( lwork ) work, integer lwork, double precision, dimension( 2 ) result)

DHST01

Purpose:

     DHST01 tests the reduction of a general matrix A to upper Hessenberg
     form:  A = Q*H*Q'.  Two test ratios are computed;
     RESULT(1) = norm( A - Q*H*Q' ) / ( norm(A) * N * EPS )
     RESULT(2) = norm( I - Q'*Q ) / ( N * EPS )
     The matrix Q is assumed to be given explicitly as it would be
     following DGEHRD + DORGHR.
     In this version, ILO and IHI are not used and are assumed to be 1 and
     N, respectively.

Parameters
    N

              N is INTEGER
              The order of the matrix A.  N >= 0.

    ILO

              ILO is INTEGER

    IHI

              IHI is INTEGER
              A is assumed to be upper triangular in rows and columns
              1:ILO-1 and IHI+1:N, so Q differs from the identity only in
              rows and columns ILO+1:IHI.

    A

              A is DOUBLE PRECISION array, dimension (LDA,N)
              The original n by n matrix A.

    LDA

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

    H

              H is DOUBLE PRECISION array, dimension (LDH,N)
              The upper Hessenberg matrix H from the reduction A = Q*H*Q'
              as computed by DGEHRD.  H is assumed to be zero below the
              first subdiagonal.

    LDH

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

    Q

              Q is DOUBLE PRECISION array, dimension (LDQ,N)
              The orthogonal matrix Q from the reduction A = Q*H*Q' as
              computed by DGEHRD + DORGHR.

    LDQ

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

    WORK

              WORK is DOUBLE PRECISION array, dimension (LWORK)

    LWORK

              LWORK is INTEGER
              The length of the array WORK.  LWORK >= 2*N*N.

    RESULT

              RESULT is DOUBLE PRECISION array, dimension (2)
              RESULT(1) = norm( A - Q*H*Q' ) / ( norm(A) * N * EPS )
              RESULT(2) = norm( I - Q'*Q ) / ( N * EPS )

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 132 of file dhst01.f.

Author

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