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SRC/lapack_64_obj/slarrc.f(3) Library Functions Manual SRC/lapack_64_obj/slarrc.f(3)

NAME

SRC/lapack_64_obj/slarrc.f

SYNOPSIS

Functions/Subroutines


subroutine SLARRC (jobt, n, vl, vu, d, e, pivmin, eigcnt, lcnt, rcnt, info)
SLARRC computes the number of eigenvalues of the symmetric tridiagonal matrix.

Function/Subroutine Documentation

subroutine SLARRC (character jobt, integer n, real vl, real vu, real, dimension( * ) d, real, dimension( * ) e, real pivmin, integer eigcnt, integer lcnt, integer rcnt, integer info)

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

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

JOBT 

!>          JOBT is CHARACTER*1
!>          = 'T':  Compute Sturm count for matrix T.
!>          = 'L':  Compute Sturm count for matrix L D L^T.
!>

N

!>          N is INTEGER
!>          The order of the matrix. N > 0.
!>

VL

!>          VL is REAL
!>          The lower bound for the eigenvalues.
!>

VU

!>          VU is REAL
!>          The upper bound for the eigenvalues.
!>

D

!>          D is REAL 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.
!>

E

!>          E is REAL 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.
!>

PIVMIN

!>          PIVMIN is REAL
!>          The minimum pivot in the Sturm sequence for T.
!>

EIGCNT

!>          EIGCNT is INTEGER
!>          The number of eigenvalues of the symmetric tridiagonal matrix T
!>          that are in the interval (VL,VU]
!>

LCNT

!>          LCNT is INTEGER
!>

RCNT

!>          RCNT is INTEGER
!>          The left and right negcounts of the interval.
!>

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

Definition at line 136 of file slarrc.f.

Author

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