TESTING/EIG/dhst01.f(3)    Library Functions Manual    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
       Generated automatically by Doxygen for LAPACK from the source code.

LAPACK                          Version 3.12.0         TESTING/EIG/dhst01.f(3)