# ?lanhp

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 matrix supplied in packed form.

## Syntax

val = clanhp( norm, uplo, n, ap, work )

val = zlanhp( norm, uplo, n, ap, work )

## Description

The function ?lanhp 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 matrix A, supplied in packed form.

## Input Parameters

norm

  CHARACTER*1. Specifies the vaule to be returned by the routine:

  = 'M' or 'm': val = max(abs(Ai j)), largest absolute value of the matrix A.

  = '1' or 'O' or 'o': val = norm1(A), 1-norm of the matrix A (maximum column sum),

  = 'I' or 'i': val = normI(A), infinity norm of the matrix A (maximum row sum),

  = 'F', 'f', 'E' or 'e': val = normF(A), Frobenius norm of the matrix A (square root of sum of squares).

uplo

  CHARACTER*1.

  Specifies whether the upper or lower triangular part of the Hermitian matrix A is supplied.

  If `uplo = 'U'`: Upper triangular part of A is supplied

  If `uplo = 'L'`: Lower triangular part of A is supplied.

n

  INTEGER. The order of the matrix A.

  `n ≥ 0`. When `n = 0`, ?lanhp is set to zero.

ap

  COMPLEX for clanhp.

  COMPLEX*16 for zlanhp.

  Array, DIMENSION (`n(n+1)/2`). The upper or lower triangle of the Hermitian matrix A, packed columnwise in a linear array. The j-th column of A is stored in the array ap as follows:

  if `uplo = 'U'`, `ap(i + (j-1)j/2) = A(i,j)` for `1 ≤ i ≤ j`;

  if `uplo = 'L'`, `ap(i + (j-1)(2n-j)/2) = A(i,j)` for `j ≤ i ≤ n`.

work

  REAL for clanhp.

  DOUBLE PRECISION for zlanhp.

  Workspace array, DIMENSION `(max(1,lwork))`, where

  `lwork ≥ n` when `norm = 'I'` or '1' or 'O'; otherwise, work is not referenced.

## Output Parameters

val

  REAL for clanhp.

  DOUBLE PRECISION for zlanhp.

  Value returned by the function.

Parent topic: Auxiliary Routines