DLANHS(3)      LAPACK routine of NEC Numeric Library Collection      DLANHS(3)



NAME
       DLANHS

SYNOPSIS
       DOUBLE PRECISION FUNCTION DLANHS (NORM, N, A, LDA, WORK)



PURPOSE
            DLANHS  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:
           DLANHS

               DLANHS = ( 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.




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

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

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

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



LAPACK routine                  31 October 2017                      DLANHS(3)