LANHT - 5.2 English - 68552

AOCL API Guide (68552)

Document ID
68552
Release Date
2025-12-29
Version
5.2 English
template<typename T, typename Ta>
Ta lanht(char *norm, integer *n, Ta *d, T *e)#

LANHT returns the value of the 1-norm, or the Frobenius norm, or the infinity norm,

or the element of largest absolute value of a complex Hermitian tridiagonal matrix.

Purpose:

   LANHT returns the value of the one norm, or the Frobenius norm, or
   the infinity norm, or the element of largest absolute value of a
   complex Hermitian tridiagonal matrix A.

   \  return CLANHT


      CLANHT = (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 CLANHT as described above.

  • N[in]

    N is INTEGER

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

  • D[in]

    D is REAL array, dimension (N)

    The diagonal elements of A.

  • E[in]

    E is COMPLEX array, dimension (N-1)

    The (n-1) sub-diagonal or super-diagonal elements of A.

Returns:

Returns the value of norm.