CLANHS(l) ) CLANHS(l)NAME
CLANHS - return the value of the one norm, or the Frobenius norm, or
the infinity norm, or the element of largest absolute value of a Hes‐
senberg matrix A
SYNOPSIS
REAL FUNCTION CLANHS( NORM, N, A, LDA, WORK )
CHARACTER NORM
INTEGER LDA, N
REAL WORK( * )
COMPLEX A( LDA, * )
PURPOSE
CLANHS returns the value of the one norm, or the Frobenius norm, or the
infinity norm, or the element of largest absolute value of a Hessenberg
matrix A.
DESCRIPTION
CLANHS returns the value
CLANHS = ( max(abs(A(i,j))), NORM = 'M' or 'm'
(
( norm1(A), NORM = '1', 'O' or 'o'
(
( normI(A), NORM = 'I' or 'i'
(
( normF(A), NORM = 'F', 'f', 'E' or 'e'
where norm1 denotes the one norm of a matrix (maximum column sum),
normI denotes the infinity norm of a matrix (maximum row sum) and
normF denotes the Frobenius norm of a matrix (square root of sum of
squares). Note that max(abs(A(i,j))) is not a matrix norm.
ARGUMENTS
NORM (input) CHARACTER*1
Specifies the value to be returned in CLANHS as described
above.
N (input) INTEGER
The order of the matrix A. N >= 0. When N = 0, CLANHS is set
to zero.
A (input) COMPLEX array, dimension (LDA,N)
The n by n upper Hessenberg matrix A; the part of A below the
first sub-diagonal is not referenced.
LDA (input) INTEGER
The leading dimension of the array A. LDA >= max(N,1).
WORK (workspace) REAL array, dimension (LWORK),
where LWORK >= N when NORM = 'I'; otherwise, WORK is not refer‐
enced.
LAPACK version 3.0 15 June 2000 CLANHS(l)
