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dlanhs

 NAME
      DLANHS - return the value of the one norm, or the Frobenius
      norm, or the infinity norm, or the element of largest abso-
      lute value of a Hessenberg matrix A

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

          CHARACTER    NORM

          INTEGER      LDA, N

          DOUBLE       PRECISION 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.

 DESCRIPTION
      DLANHS returns the value

         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  matrix norm.

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

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

      A       (input) 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) INTEGER

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

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