
slangb.f(3) LAPACK slangb.f(3)
NAME
slangb.f 
SYNOPSIS
Functions/Subroutines
REAL function slangb (NORM, N, KL, KU, AB, LDAB, WORK)
SLANGB returns the value of the 1norm, Frobenius norm, infinitynorm, or the largest
absolute value of any element of general band matrix.
Function/Subroutine Documentation
REAL function slangb (characterNORM, integerN, integerKL, integerKU, real, dimension( ldab, *
)AB, integerLDAB, real, dimension( * )WORK)
SLANGB returns the value of the 1norm, Frobenius norm, infinitynorm, or the largest
absolute value of any element of general band matrix.
Purpose:
SLANGB 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 subdiagonals and ku superdiagonals.
Returns:
SLANGB
SLANGB = ( 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 SLANGB as described
above.
N
N is INTEGER
The order of the matrix A. N >= 0. When N = 0, SLANGB is
set to zero.
KL
KL is INTEGER
The number of subdiagonals of the matrix A. KL >= 0.
KU
KU is INTEGER
The number of superdiagonals of the matrix A. KU >= 0.
AB
AB is REAL array, dimension (LDAB,N)
The band matrix A, stored in rows 1 to KL+KU+1. The jth
column of A is stored in the jth column of the array AB as
follows:
AB(ku+1+ij,j) = A(i,j) for max(1,jku)<=i<=min(n,j+kl).
LDAB
LDAB is INTEGER
The leading dimension of the array AB. LDAB >= KL+KU+1.
WORK
WORK is REAL array, dimension (MAX(1,LWORK)),
where LWORK >= N when NORM = 'I'; otherwise, WORK is not
referenced.
Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
September 2012
Definition at line 124 of file slangb.f.
Author
Generated automatically by Doxygen for LAPACK from the source code.
Version 3.4.2 Tue Sep 25 2012 slangb.f(3) 
