zlaqsb.f (3)  Linux Manuals
NAME
zlaqsb.f 
SYNOPSIS
Functions/Subroutines
subroutine zlaqsb (UPLO, N, KD, AB, LDAB, S, SCOND, AMAX, EQUED)
ZLAQSB scales a symmetric/Hermitian band matrix, using scaling factors computed by spbequ.
Function/Subroutine Documentation
subroutine zlaqsb (characterUPLO, integerN, integerKD, complex*16, dimension( ldab, * )AB, integerLDAB, double precision, dimension( * )S, double precisionSCOND, double precisionAMAX, characterEQUED)
ZLAQSB scales a symmetric/Hermitian band matrix, using scaling factors computed by spbequ.
Purpose:

ZLAQSB equilibrates a symmetric band matrix A using the scaling factors in the vector S.
Parameters:

UPLO
UPLO is CHARACTER*1 Specifies whether the upper or lower triangular part of the symmetric matrix A is stored. = 'U': Upper triangular = 'L': Lower triangular
NN is INTEGER The order of the matrix A. N >= 0.
KDKD is INTEGER The number of superdiagonals of the matrix A if UPLO = 'U', or the number of subdiagonals if UPLO = 'L'. KD >= 0.
ABAB is COMPLEX*16 array, dimension (LDAB,N) On entry, the upper or lower triangle of the symmetric band matrix A, stored in the first KD+1 rows of the array. The jth column of A is stored in the jth column of the array AB as follows: if UPLO = 'U', AB(kd+1+ij,j) = A(i,j) for max(1,jkd)<=i<=j; if UPLO = 'L', AB(1+ij,j) = A(i,j) for j<=i<=min(n,j+kd). On exit, if INFO = 0, the triangular factor U or L from the Cholesky factorization A = U**H *U or A = L*L**H of the band matrix A, in the same storage format as A.
LDABLDAB is INTEGER The leading dimension of the array AB. LDAB >= KD+1.
SS is DOUBLE PRECISION array, dimension (N) The scale factors for A.
SCONDSCOND is DOUBLE PRECISION Ratio of the smallest S(i) to the largest S(i).
AMAXAMAX is DOUBLE PRECISION Absolute value of largest matrix entry.
EQUEDEQUED is CHARACTER*1 Specifies whether or not equilibration was done. = 'N': No equilibration. = 'Y': Equilibration was done, i.e., A has been replaced by diag(S) * A * diag(S).
Internal Parameters:

THRESH is a threshold value used to decide if scaling should be done based on the ratio of the scaling factors. If SCOND < THRESH, scaling is done. LARGE and SMALL are threshold values used to decide if scaling should be done based on the absolute size of the largest matrix element. If AMAX > LARGE or AMAX < SMALL, scaling is done.
Author:

Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
 September 2012
Definition at line 142 of file zlaqsb.f.
Author
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