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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