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zlangt.f -

# SYNOPSIS

## Functions/Subroutines

DOUBLE PRECISION function zlangt (NORM, N, DL, D, DU)

ZLANGT returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value of any element of a general tridiagonal matrix.

# Function/Subroutine Documentation

## DOUBLE PRECISION function zlangt (characterNORM, integerN, complex*16, dimension( * )DL, complex*16, dimension( * )D, complex*16, dimension( * )DU)

ZLANGT returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value of any element of a general tridiagonal matrix.
Purpose:
``` ZLANGT  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 tridiagonal matrix A.
```
Returns:
ZLANGT
```    ZLANGT = ( 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 ZLANGT as described
above.
```
N
```          N is INTEGER
The order of the matrix A.  N >= 0.  When N = 0, ZLANGT is
set to zero.
```
DL
```          DL is COMPLEX*16 array, dimension (N-1)
The (n-1) sub-diagonal elements of A.
```
D
```          D is COMPLEX*16 array, dimension (N)
The diagonal elements of A.
```
DU
```          DU is COMPLEX*16 array, dimension (N-1)
The (n-1) super-diagonal elements of A.
```
Author:
Univ. of Tennessee
Univ. of California Berkeley
NAG Ltd.
Date:
September 2012
Definition at line 107 of file zlangt.f.

# Author

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