# ?lanhe

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.

## Syntax

val = clanhe( norm, uplo, n, a, lda, work )

val = zlanhe( norm, uplo, n, a, lda, work )

## Description

The function ?lanhe 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.

## 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 to be referenced.

  = 'U': Upper triangular part of A is referenced.

  = 'L': Lower triangular part of A is referenced

n

  INTEGER. The order of the matrix A. `n ≥ 0`. When `n = 0`, ?lanhe is set to zero.

a

  COMPLEX for clanhe.

  COMPLEX*16 for zlanhe.

  Array, DIMENSION (lda,n). The Hermitian matrix A.

  If `uplo = 'U'`, the leading n-by-n upper triangular part of a contains the upper triangular part of the matrix A, and the strictly lower triangular part of a is not referenced.

  If `uplo = 'L'`, the leading n-by-n lower triangular part of a contains the lower triangular part of the matrix A, and the strictly upper triangular part of a is not referenced.

lda

  INTEGER. The leading dimension of the array a.

  `lda ≥ max(n,1)`.

work

  REAL for clanhe.

  DOUBLE PRECISION for zlanhe.

  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 clanhe.

  DOUBLE PRECISION for zlanhe.

  Value returned by the function.

Parent topic: Auxiliary Routines