org.netlib.lapack
Class DLARRB

java.lang.Object
  org.netlib.lapack.DLARRB

public class DLARRB
extends java.lang.Object

DLARRB is a simplified interface to the JLAPACK routine dlarrb.
This interface converts Java-style 2D row-major arrays into
the 1D column-major linearized arrays expected by the lower
level JLAPACK routines.  Using this interface also allows you
to omit offset and leading dimension arguments.  However, because
of these conversions, these routines will be slower than the low
level ones.  Following is the description from the original Fortran
source.  Contact seymour@cs.utk.edu with any questions.

 *     ..
 *
 *  Purpose
 *  =======
 *
 *  Given the relatively robust representation(RRR) L D L^T, DLARRB
 *  does ``limited'' bisection to locate the eigenvalues of L D L^T,
 *  W( IFIRST ) thru' W( ILAST ), to more accuracy. Intervals
 *  [left, right] are maintained by storing their mid-points and
 *  semi-widths in the arrays W and WERR respectively.
 *
 *  Arguments
 *  =========
 *
 *  N       (input) INTEGER
 *          The order of the matrix.
 *
 *  D       (input) DOUBLE PRECISION array, dimension (N)
 *          The n diagonal elements of the diagonal matrix D.
 *
 *  L       (input) DOUBLE PRECISION array, dimension (N-1)
 *          The n-1 subdiagonal elements of the unit bidiagonal matrix L.
 *
 *  LD      (input) DOUBLE PRECISION array, dimension (N-1)
 *          The n-1 elements L(i)*D(i).
 *
 *  LLD     (input) DOUBLE PRECISION array, dimension (N-1)
 *          The n-1 elements L(i)*L(i)*D(i).
 *
 *  IFIRST  (input) INTEGER
 *          The index of the first eigenvalue in the cluster.
 *
 *  ILAST   (input) INTEGER
 *          The index of the last eigenvalue in the cluster.
 *
 *  SIGMA   (input) DOUBLE PRECISION
 *          The shift used to form L D L^T (see DLARRF).
 *
 *  RELTOL  (input) DOUBLE PRECISION
 *          The relative tolerance.
 *
 *  W       (input/output) DOUBLE PRECISION array, dimension (N)
 *          On input, W( IFIRST ) thru' W( ILAST ) are estimates of the
 *          corresponding eigenvalues of L D L^T.
 *          On output, these estimates are ``refined''.
 *
 *  WGAP    (input/output) DOUBLE PRECISION array, dimension (N)
 *          The gaps between the eigenvalues of L D L^T. Very small
 *          gaps are changed on output.
 *
 *  WERR    (input/output) DOUBLE PRECISION array, dimension (N)
 *          On input, WERR( IFIRST ) thru' WERR( ILAST ) are the errors
 *          in the estimates W( IFIRST ) thru' W( ILAST ).
 *          On output, these are the ``refined'' errors.
 *
 *****Reminder to Inder --- WORK is never used in this subroutine *****
 *  WORK    (input) DOUBLE PRECISION array, dimension (???)
 *          Workspace.
 *
 *  IWORK   (input) INTEGER array, dimension (2*N)
 *          Workspace.
 *
 *****Reminder to Inder --- INFO is never set in this subroutine ******
 *  INFO    (output) INTEGER
 *          Error flag.
 *
 *  Further Details
 *  ===============
 *
 *  Based on contributions by
 *     Inderjit Dhillon, IBM Almaden, USA
 *     Osni Marques, LBNL/NERSC, USA
 *
 *  =====================================================================
 *
 *     .. Parameters ..

Constructor Summary

DLARRB()

Method Summary

static void

DLARRB(int n, double[] d, double[] l, double[] ld, double[] lld, int ifirst, int ilast, double sigma, double reltol, double[] w, double[] wgap, double[] werr, double[] work, int[] iwork, int info)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DLARRB

public DLARRB()

Method Detail

DLARRB

public static void DLARRB(int n,
                          double[] d,
                          double[] l,
                          double[] ld,
                          double[] lld,
                          int ifirst,
                          int ilast,
                          double sigma,
                          double reltol,
                          double[] w,
                          double[] wgap,
                          double[] werr,
                          double[] work,
                          int[] iwork,
                          int info)