cptcon()

subroutine cptcon	(	integer	n,
		real, dimension( * )	d,
		complex, dimension( * )	e,
		real	anorm,
		real	rcond,
		real, dimension( * )	rwork,
		integer	info )

CPTCON

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Purpose:

!>
!> CPTCON computes the reciprocal of the condition number (in the
!> 1-norm) of a complex Hermitian positive definite tridiagonal matrix
!> using the factorization A = L*D*L**H or A = U**H*D*U computed by
!> CPTTRF.
!>
!> Norm(inv(A)) is computed by a direct method, and the reciprocal of
!> the condition number is computed as
!>                  RCOND = 1 / (ANORM * norm(inv(A))).
!> 

Parameters

[in]	N	!> N is INTEGER !> The order of the matrix A. N >= 0. !>
[in]	D	!> D is REAL array, dimension (N) !> The n diagonal elements of the diagonal matrix D from the !> factorization of A, as computed by CPTTRF. !>
[in]	E	!> E is COMPLEX array, dimension (N-1) !> The (n-1) off-diagonal elements of the unit bidiagonal factor !> U or L from the factorization of A, as computed by CPTTRF. !>
[in]	ANORM	!> ANORM is REAL !> The 1-norm of the original 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 the !> 1-norm of inv(A) computed in this routine. !>
[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.

Further Details:

!>
!>  The method used is described in Nicholas J. Higham, , SIAM J. Sci. Stat. Comput., Vol. 7, No. 1, January 1986.
!>