dlansb.f (3)  Linux Manuals
NAME
dlansb.f 
SYNOPSIS
Functions/Subroutines
DOUBLE PRECISION function dlansb (NORM, UPLO, N, K, AB, LDAB, WORK)
DLANSB returns the value of the 1norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a symmetric band matrix.
Function/Subroutine Documentation
DOUBLE PRECISION function dlansb (characterNORM, characterUPLO, integerN, integerK, double precision, dimension( ldab, * )AB, integerLDAB, double precision, dimension( * )WORK)
DLANSB returns the value of the 1norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a symmetric band matrix.
Purpose:

DLANSB 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 symmetric band matrix A, with k superdiagonals.
Returns:

DLANSB
DLANSB = ( 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 DLANSB as described above.
UPLOUPLO is CHARACTER*1 Specifies whether the upper or lower triangular part of the band matrix A is supplied. = 'U': Upper triangular part is supplied = 'L': Lower triangular part is supplied
NN is INTEGER The order of the matrix A. N >= 0. When N = 0, DLANSB is set to zero.
KK is INTEGER The number of superdiagonals or subdiagonals of the band matrix A. K >= 0.
ABAB is DOUBLE PRECISION array, dimension (LDAB,N) The upper or lower triangle of the symmetric band matrix A, stored in the first K+1 rows of AB. The jth column of A is stored in the jth column of the array AB as follows: if UPLO = 'U', AB(k+1+ij,j) = A(i,j) for max(1,jk)<=i<=j; if UPLO = 'L', AB(1+ij,j) = A(i,j) for j<=i<=min(n,j+k).
LDABLDAB is INTEGER The leading dimension of the array AB. LDAB >= K+1.
WORKWORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK)), where LWORK >= N when NORM = 'I' or '1' or 'O'; 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 129 of file dlansb.f.
Author
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