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