dlarrc()

subroutine dlarrc	(	character	jobt,
		integer	n,
		double precision	vl,
		double precision	vu,
		double precision, dimension( * )	d,
		double precision, dimension( * )	e,
		double precision	pivmin,
		integer	eigcnt,
		integer	lcnt,
		integer	rcnt,
		integer	info )

DLARRC computes the number of eigenvalues of the symmetric tridiagonal matrix.

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Purpose:

!>
!> Find the number of eigenvalues of the symmetric tridiagonal matrix T
!> that are in the interval (VL,VU] if JOBT = 'T', and of L D L^T
!> if JOBT = 'L'.
!> 

Parameters

[in]	JOBT	!> JOBT is CHARACTER*1 !> = 'T': Compute Sturm count for matrix T. !> = 'L': Compute Sturm count for matrix L D L^T. !>
[in]	N	!> N is INTEGER !> The order of the matrix. N > 0. !>
[in]	VL	!> VL is DOUBLE PRECISION !> The lower bound for the eigenvalues. !>
[in]	VU	!> VU is DOUBLE PRECISION !> The upper bound for the eigenvalues. !>
[in]	D	!> D is DOUBLE PRECISION array, dimension (N) !> JOBT = 'T': The N diagonal elements of the tridiagonal matrix T. !> JOBT = 'L': The N diagonal elements of the diagonal matrix D. !>
[in]	E	!> E is DOUBLE PRECISION array, dimension (N) !> JOBT = 'T': The N-1 offdiagonal elements of the matrix T. !> JOBT = 'L': The N-1 offdiagonal elements of the matrix L. !>
[in]	PIVMIN	!> PIVMIN is DOUBLE PRECISION !> The minimum pivot in the Sturm sequence for T. !>
[out]	EIGCNT	!> EIGCNT is INTEGER !> The number of eigenvalues of the symmetric tridiagonal matrix T !> that are in the interval (VL,VU] !>
[out]	LCNT	!> LCNT is INTEGER !>
[out]	RCNT	!> RCNT is INTEGER !> The left and right negcounts of the interval. !>
[out]	INFO	!> INFO is INTEGER !>

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Contributors:

Beresford Parlett, University of California, Berkeley, USA
Jim Demmel, University of California, Berkeley, USA
Inderjit Dhillon, University of Texas, Austin, USA
Osni Marques, LBNL/NERSC, USA
Christof Voemel, University of California, Berkeley, USA