LANHS - 5.2 English - 68552

LANHS 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:

 LANHS 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.

    SLANHS = (fla_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  fla_max(abs(A(i,j)))  is not a consistent matrix norm.

Parameters:

• NORM – [in]

  NORM is CHARACTER*1

  Specifies the value to be returned in SLANHS as described above.

• N – [in]

  N is INTEGER

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

• A – [in]

  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 – [in]

  LDA is INTEGER

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

• WORK – [out]

  WORK is REAL array, dimension (MAX(1,LWORK)),

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

Returns:

Returns the value of norm.