# ?lanst/?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 real symmetric or complex Hermitian tridiagonal matrix.

## Syntax

val = slanst( norm, n, d, e )

val = dlanst( norm, n, d, e )

val = clanht( norm, n, d, e )

val = zlanht( norm, n, d, e )

## Include Files

• Fortran: mkl.fi
• C: mkl.h

## Description

The functions ?lanst/?lanht return the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a real symmetric or a complex Hermitian tridiagonal matrix A.

## Input Parameters

norm

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

= 'M' or 'm': `val = max(abs(Aij))`, 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).

n

INTEGER. The order of the matrix A.

`n ≥ 0`. When `n = 0`, ?lanst/?lanht is set to zero.

d

REAL for slanst/clanht

DOUBLE PRECISION for dlanst/zlanht

Array, DIMENSION (n). The diagonal elements of A.

e

REAL for slanst

DOUBLE PRECISION for dlanst

COMPLEX for clanht

DOUBLE COMPLEX for zlanht

Array, DIMENSION (n-1).

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

## Output Parameters

val

REAL for slanst/clanht

DOUBLE PRECISION for dlanst/zlanht

Value returned by the function.

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