# CentOS 7.0 - man page for slanhs (centos section 3)

```slanhs.f(3)							      LAPACK							       slanhs.f(3)

NAME
slanhs.f -

SYNOPSIS
Functions/Subroutines
REAL function slanhs (NORM, N, A, LDA, WORK)
SLANHS returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value of any element of an upper
Hessenberg matrix.

Function/Subroutine Documentation
REAL function slanhs (characterNORM, integerN, real, dimension( lda, * )A, integerLDA, real, dimension( * )WORK)
SLANHS returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value of any element of an upper Hessenberg
matrix.

Purpose:

SLANHS  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.

Returns:
SLANHS

SLANHS = ( 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 consistent matrix norm.

Parameters:
NORM

NORM is CHARACTER*1
Specifies the value to be returned in SLANHS as described
above.

N

N is INTEGER
The order of the matrix A.  N >= 0.  When N = 0, SLANHS is
set to zero.

A

A is REAL 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

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

WORK

WORK is REAL array, dimension (MAX(1,LWORK)),
where LWORK >= N when NORM = 'I'; otherwise, WORK is not
referenced.

Author:
Univ. of Tennessee

Univ. of California Berkeley