TESTING/EIG/shst01.f(3)    Library Functions Manual    TESTING/EIG/shst01.f(3)

NAME
       TESTING/EIG/shst01.f

SYNOPSIS
   Functions/Subroutines
       subroutine shst01 (n, ilo, ihi, a, lda, h, ldh, q, ldq, work, lwork,
           result)
           SHST01

Function/Subroutine Documentation
   subroutine shst01 (integer n, integer ilo, integer ihi, real, dimension(
       lda, * ) a, integer lda, real, dimension( ldh, * ) h, integer ldh,
       real, dimension( ldq, * ) q, integer ldq, real, dimension( lwork )
       work, integer lwork, real, dimension( 2 ) result)
       SHST01

       Purpose:


            SHST01 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 SGEHRD + SORGHR.

            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 REAL 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 REAL array, dimension (LDH,N)
                     The upper Hessenberg matrix H from the reduction A = Q*H*Q'
                     as computed by SGEHRD.  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 REAL array, dimension (LDQ,N)
                     The orthogonal matrix Q from the reduction A = Q*H*Q' as
                     computed by SGEHRD + SORGHR.

           LDQ

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

           WORK

                     WORK is REAL array, dimension (LWORK)

           LWORK

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

           RESULT

                     RESULT is REAL 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 shst01.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

LAPACK                          Version 3.12.0         TESTING/EIG/shst01.f(3)