slangb.f (3)  Linux Man Pages
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.
NN is INTEGER The order of the matrix A. N >= 0. When N = 0, SLANGB is set to zero.
KLKL is INTEGER The number of subdiagonals of the matrix A. KL >= 0.
KUKU is INTEGER The number of superdiagonals of the matrix A. KU >= 0.
ABAB 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).
LDABLDAB is INTEGER The leading dimension of the array AB. LDAB >= KL+KU+1.
WORKWORK 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
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