SLANHS  -  return the value of the one norm, or the Frobe­
       nius 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   Frobe­
       nius  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).

               where  LWORK >= N when NORM = 'I'; otherwise, WORK
               is not referenced.


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