cpbcon()

subroutine cpbcon	(	character	uplo,
		integer	n,
		integer	kd,
		complex, dimension( ldab, * )	ab,
		integer	ldab,
		real	anorm,
		real	rcond,
		complex, dimension( * )	work,
		real, dimension( * )	rwork,
		integer	info )

CPBCON

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Purpose:

!>
!> CPBCON estimates the reciprocal of the condition number (in the
!> 1-norm) of a complex Hermitian positive definite band matrix using
!> the Cholesky factorization A = U**H*U or A = L*L**H computed by
!> CPBTRF.
!>
!> An estimate is obtained for norm(inv(A)), and the reciprocal of the
!> condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))).
!> 

Parameters

[in]	UPLO	!> UPLO is CHARACTER*1 !> = 'U': Upper triangular factor stored in AB; !> = 'L': Lower triangular factor stored in AB. !>
[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 sub-diagonals if UPLO = 'L'. KD >= 0. !>
[in]	AB	!> AB is COMPLEX array, dimension (LDAB,N) !> The triangular factor U or L from the Cholesky factorization !> A = U**H*U or A = L*L**H of the band matrix A, stored in the !> first KD+1 rows of the array. The j-th column of U or L is !> stored in the j-th column of the array AB as follows: !> if UPLO ='U', AB(kd+1+i-j,j) = U(i,j) for max(1,j-kd)<=i<=j; !> if UPLO ='L', AB(1+i-j,j) = L(i,j) for j<=i<=min(n,j+kd). !>
[in]	LDAB	!> LDAB is INTEGER !> The leading dimension of the array AB. LDAB >= KD+1. !>
[in]	ANORM	!> ANORM is REAL !> The 1-norm (or infinity-norm) of the Hermitian band matrix A. !>
[out]	RCOND	!> RCOND is REAL !> The reciprocal of the condition number of the matrix A, !> computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is an !> estimate of the 1-norm of inv(A) computed in this routine. !>
[out]	WORK	!> WORK is COMPLEX array, dimension (2*N) !>
[out]	RWORK	!> RWORK is REAL array, dimension (N) !>
[out]	INFO	!> INFO is INTEGER !> = 0: successful exit !> < 0: if INFO = -i, the i-th argument had an illegal value !>

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.