
NAMEzlaqhb.f SYNOPSISFunctions/Subroutinessubroutine zlaqhb (UPLO, N, KD, AB, LDAB, S, SCOND, AMAX, EQUED) Function/Subroutine Documentationsubroutine zlaqhb (characterUPLO, integerN, integerKD, complex*16, dimension( ldab, * )AB, integerLDAB, double precision, dimension( * )S, double precisionSCOND, double precisionAMAX, characterEQUED)ZLAQHB scales a Hermitian band matrix, using scaling factors computed by cpbequ. Purpose:ZLAQHB equilibrates a Hermitian band matrix A using the scaling factors in the vector S. UPLO
Internal Parameters:
UPLO is CHARACTER*1 Specifies whether the upper or lower triangular part of the symmetric matrix A is stored. = 'U': Upper triangular = 'L': Lower triangularN N is INTEGER The order of the matrix A. N >= 0.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.AB AB 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.LDAB LDAB is INTEGER The leading dimension of the array AB. LDAB >= KD+1.S S is DOUBLE PRECISION array, dimension (N) The scale factors for A.SCOND SCOND is DOUBLE PRECISION Ratio of the smallest S(i) to the largest S(i).AMAX AMAX is DOUBLE PRECISION Absolute value of largest matrix entry.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 = 'Y': Equilibration was done, i.e., A has been replaced by diag(S) * A * diag(S).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. Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
September 2012
Definition at line 142 of file zlaqhb.f.
AuthorGenerated automatically by Doxygen for LAPACK from the source code.
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