# CentOS 7.0 - man page for dlangb (centos section 3)

```dlangb.f(3)							      LAPACK							       dlangb.f(3)

NAME
dlangb.f -

SYNOPSIS
Functions/Subroutines
DOUBLE PRECISION function dlangb (NORM, N, KL, KU, AB, LDAB, WORK)
DLANGB returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value of any element of general band
matrix.

Function/Subroutine Documentation
DOUBLE PRECISION function dlangb (characterNORM, integerN, integerKL, integerKU, double precision, dimension( ldab, * )AB, integerLDAB, double
precision, dimension( * )WORK)
DLANGB returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value of any element of general band matrix.

Purpose:

DLANGB  returns the value of the one norm,	or the Frobenius norm, or
the  infinity norm,  or the element of  largest absolute value  of an
n by n band matrix	A,  with kl sub-diagonals and ku super-diagonals.

Returns:
DLANGB

DLANGB = ( 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 DLANGB as described
above.

N

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

KL

KL is INTEGER
The number of sub-diagonals of the matrix A.  KL >= 0.

KU

KU is INTEGER
The number of super-diagonals of the matrix A.  KU >= 0.

AB

AB is DOUBLE PRECISION array, dimension (LDAB,N)
The band matrix A, stored in rows 1 to KL+KU+1.  The j-th
column of A is stored in the j-th column of the array AB as
follows:
AB(ku+1+i-j,j) = A(i,j) for max(1,j-ku)<=i<=min(n,j+kl).

LDAB

LDAB is INTEGER
The leading dimension of the array AB.  LDAB >= KL+KU+1.

WORK

WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK)),
where LWORK >= N when NORM = 'I'; otherwise, WORK is not
referenced.

Author:
Univ. of Tennessee

Univ. of California Berkeley

NAG Ltd.

Date:
September 2012

Definition at line 124 of file dlangb.f.

Author
Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.2							  Tue Sep 25 2012						       dlangb.f(3)```
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