TESTING/EIG/chst01.f(3) | Library Functions Manual | TESTING/EIG/chst01.f(3) |
NAME
TESTING/EIG/chst01.f
SYNOPSIS
Functions/Subroutines
subroutine chst01 (n, ilo, ihi, a, lda, h, ldh, q, ldq,
work, lwork, rwork, result)
CHST01
Function/Subroutine Documentation
subroutine chst01 (integer n, integer ilo, integer ihi, complex, dimension( lda, * ) a, integer lda, complex, dimension( ldh, * ) h, integer ldh, complex, dimension( ldq, * ) q, integer ldq, complex, dimension( lwork ) work, integer lwork, real, dimension( * ) rwork, real, dimension( 2 ) result)
CHST01
Purpose:
CHST01 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 CGEHRD + CUNGHR. In this version, ILO and IHI are not used, but they could be used to save some work if this is desired.
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 COMPLEX 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 COMPLEX array, dimension (LDH,N) The upper Hessenberg matrix H from the reduction A = Q*H*Q' as computed by CGEHRD. 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 COMPLEX array, dimension (LDQ,N) The orthogonal matrix Q from the reduction A = Q*H*Q' as computed by CGEHRD + CUNGHR.
LDQ
LDQ is INTEGER The leading dimension of the array Q. LDQ >= max(1,N).
WORK
WORK is COMPLEX array, dimension (LWORK)
LWORK
LWORK is INTEGER The length of the array WORK. LWORK >= 2*N*N.
RWORK
RWORK is REAL array, dimension (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 138 of file chst01.f.
Author
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