# dlanst.f - Man Page

SRC/dlanst.f

## Synopsis

### Functions/Subroutines

double precision function dlanst (norm, n, d, e)
DLANST 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 tridiagonal matrix.

## Function/Subroutine Documentation

### double precision function dlanst (character norm, integer n, double precision, dimension( * ) d, double precision, dimension( * ) e)

DLANST 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 tridiagonal matrix.

Purpose:

``` DLANST  returns the value of the one norm,  or the Frobenius norm, or
the  infinity norm,  or the  element of  largest absolute value  of a
real symmetric tridiagonal matrix A.```
Returns

DLANST

```    DLANST = ( 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  max(abs(A(i,j)))  is not a consistent matrix norm.```
Parameters

NORM

```          NORM is CHARACTER*1
Specifies the value to be returned in DLANST as described
above.```

N

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

D

```          D is DOUBLE PRECISION array, dimension (N)
The diagonal elements of A.```

E

```          E is DOUBLE PRECISION array, dimension (N-1)
The (n-1) sub-diagonal or super-diagonal elements of A.```
Author

Univ. of Tennessee

Univ. of California Berkeley

NAG Ltd.

Definition at line 99 of file dlanst.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page dlanst(3) is an alias of dlanst.f(3).

Tue Nov 28 2023 12:08:42 Version 3.12.0 LAPACK