LAPACK
3.4.2
LAPACK: Linear Algebra PACKage

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Functions/Subroutines  
subroutine  dlaqsb (UPLO, N, KD, AB, LDAB, S, SCOND, AMAX, EQUED) 
DLAQSB scales a symmetric/Hermitian band matrix, using scaling factors computed by spbequ. 
subroutine dlaqsb  (  character  UPLO, 
integer  N,  
integer  KD,  
double precision, dimension( ldab, * )  AB,  
integer  LDAB,  
double precision, dimension( * )  S,  
double precision  SCOND,  
double precision  AMAX,  
character  EQUED  
) 
DLAQSB scales a symmetric/Hermitian band matrix, using scaling factors computed by spbequ.
Download DLAQSB + dependencies [TGZ] [ZIP] [TXT]DLAQSB equilibrates a symmetric band matrix A using the scaling factors in the vector S.
[in]  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 
[in]  N  N is INTEGER The order of the matrix A. N >= 0. 
[in]  KD  KD is INTEGER The number of superdiagonals of the matrix A if UPLO = 'U', or the number of subdiagonals if UPLO = 'L'. KD >= 0. 
[in,out]  AB  AB is DOUBLE PRECISION 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**T*U or A = L*L**T of the band matrix A, in the same storage format as A. 
[in]  LDAB  LDAB is INTEGER The leading dimension of the array AB. LDAB >= KD+1. 
[in]  S  S is DOUBLE PRECISION array, dimension (N) The scale factors for A. 
[in]  SCOND  SCOND is DOUBLE PRECISION Ratio of the smallest S(i) to the largest S(i). 
[in]  AMAX  AMAX is DOUBLE PRECISION Absolute value of largest matrix entry. 
[out]  EQUED  EQUED 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 = 'Y': Equilibration was done, i.e., A has been replaced by diag(S) * A * diag(S). 
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.
Definition at line 141 of file dlaqsb.f.