slanhs(3F)

NAME
     SLANHS - return 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

SYNOPSIS
     REAL FUNCTION SLANHS( NORM, N, A, LDA, WORK )

         CHARACTER NORM

         INTEGER   LDA, N

         REAL      A( LDA, * ), WORK( * )

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.


DESCRIPTION
     SLANHS returns the value

        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  matrix norm.


ARGUMENTS
     NORM    (input) CHARACTER*1
             Specifies the value to be returned in SLANHS as described above.

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

     A       (input) 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     (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
             referenced.