CLAQHB (3) Linux Manual Page

claqhb.f –

Synopsis

Functions/Subroutines

subroutine claqhb (UPLO, N, KD, AB, LDAB, S, SCOND, AMAX, EQUED)
CLAQHB scales a Hermitian band matrix, using scaling factors computed by cpbequ.

Function/Subroutine Documentation

subroutine claqhb (characterUPLO, integerN, integerKD, complex, dimension( ldab, * )AB, integerLDAB, real, dimension( * )S, realSCOND, realAMAX, characterEQUED)

CLAQHB scales a Hermitian band matrix, using scaling factors computed by cpbequ.

Purpose:

 CLAQHB equilibrates an Hermitian 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

N

 N is INTEGER

 The order of the matrix A. N >= 0.

KD

 KD is INTEGER

 The number of super-diagonals of the matrix A if UPLO = ‘U’,

 or the number of sub-diagonals if UPLO = ‘L’. KD >= 0.

AB

 AB is COMPLEX 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

 j-th column of A is stored in the j-th column of the array AB

 as follows:

 if UPLO = ‘U’, AB(kd+1+i-j,j) = A(i,j) for max(1,j-kd)<=i<=j;

 if UPLO = ‘L’, AB(1+i-j,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 REAL array, dimension (N)

 The scale factors for A.

SCOND

 SCOND is REAL

 Ratio of the smallest S(i) to the largest S(i).

AMAX

 AMAX is REAL

 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 = ‘Y’: Equilibration was done, i.e., A has been replaced by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).

 

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 claqhb.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.