dlarrc.f(3)

NAME
dlarrc.f

SYNOPSIS

  Functions/Subroutines
subroutine dlarrc (JOBT, N, VL, VU, D, E, PIVMIN, EIGCNT, LCNT, RCNT, INFO)
DLARRC computes the number of eigenvalues of the symmetric tridiagonal matrix.

Function/Subroutine Documentation

  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.

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 DOUBLE PRECISION
              The lower bound for the eigenvalues.

    VU

              VU is DOUBLE PRECISION
              The upper bound for the eigenvalues.

    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.

    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.

    PIVMIN

              PIVMIN is DOUBLE PRECISION
              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.

Date:
    June 2016

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 139 of file dlarrc.f.

Author

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