SRC/slarrc.f(3)

NAME
SRC/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 135 of file slarrc.f.

Author

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