zpttrf()

subroutine zpttrf	(	integer	n,
		double precision, dimension( * )	d,
		complex*16, dimension( * )	e,
		integer	info )

ZPTTRF

Download ZPTTRF + dependencies [TGZ] [ZIP] [TXT]

Purpose:

!>
!> ZPTTRF computes the L*D*L**H factorization of a complex Hermitian
!> positive definite tridiagonal matrix A.  The factorization may also
!> be regarded as having the form A = U**H *D*U.
!> 

Parameters

[in]	N	!> N is INTEGER !> The order of the matrix A. N >= 0. !>
[in,out]	D	!> D is DOUBLE PRECISION array, dimension (N) !> On entry, the n diagonal elements of the tridiagonal matrix !> A. On exit, the n diagonal elements of the diagonal matrix !> D from the L*D*L**H factorization of A. !>
[in,out]	E	!> E is COMPLEX*16 array, dimension (N-1) !> On entry, the (n-1) subdiagonal elements of the tridiagonal !> matrix A. On exit, the (n-1) subdiagonal elements of the !> unit bidiagonal factor L from the L*D*L**H factorization of A. !> E can also be regarded as the superdiagonal of the unit !> bidiagonal factor U from the U**H *D*U factorization of A. !>
[out]	INFO	!> INFO is INTEGER !> = 0: successful exit !> < 0: if INFO = -k, the k-th argument had an illegal value !> > 0: if INFO = k, the leading principal minor of order k !> is not positive; if k < N, the factorization could not !> be completed, while if k = N, the factorization was !> completed, but D(N) <= 0. !>

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.