org.netlib.lapack
Class SLARRB

java.lang.Object
  extended by org.netlib.lapack.SLARRB

public class SLARRB
extends java.lang.Object

SLARRB is a simplified interface to the JLAPACK routine slarrb.
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, SLARRB * does "limited" bisection to refine the eigenvalues of L D L^T, * W( IFIRST-OFFSET ) through W( ILAST-OFFSET ), to more accuracy. Initi * guesses for these eigenvalues are input in W, the corresponding estim * of the error in these guesses and their gaps are input in WERR * and WGAP, respectively. During bisection, 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) REAL array, dimension (N) * The N diagonal elements of the diagonal matrix D. * * LLD (input) REAL array, dimension (N-1) * The (N-1) elements L(i)*L(i)*D(i). * * IFIRST (input) INTEGER * The index of the first eigenvalue to be computed. * * ILAST (input) INTEGER * The index of the last eigenvalue to be computed. * * RTOL1 (input) REAL * RTOL2 (input) REAL * Tolerance for the convergence of the bisection intervals. * An interval [LEFT,RIGHT] has converged if * RIGHT-LEFT.LT.MAX( RTOL1*GAP, RTOL2*MAX(|LEFT|,|RIGHT|) ) * where GAP is the (estimated) distance to the nearest * eigenvalue. * * OFFSET (input) INTEGER * Offset for the arrays W, WGAP and WERR, i.e., the IFIRST-OFFS * through ILAST-OFFSET elements of these arrays are to be used. * * W (input/output) REAL array, dimension (N) * On input, W( IFIRST-OFFSET ) through W( ILAST-OFFSET ) are * estimates of the eigenvalues of L D L^T indexed IFIRST throug * ILAST. * On output, these estimates are refined. * * WGAP (input/output) REAL array, dimension (N-1) * On input, the (estimated) gaps between consecutive * eigenvalues of L D L^T, i.e., WGAP(I-OFFSET) is the gap betwe * eigenvalues I and I+1. Note that if IFIRST.EQ.ILAST * then WGAP(IFIRST-OFFSET) must be set to ZERO. * On output, these gaps are refined. * * WERR (input/output) REAL array, dimension (N) * On input, WERR( IFIRST-OFFSET ) through WERR( ILAST-OFFSET ) * the errors in the estimates of the corresponding elements in * On output, these errors are refined. * * WORK (workspace) REAL array, dimension (2*N) * Workspace. * * IWORK (workspace) INTEGER array, dimension (2*N) * Workspace. * * PIVMIN (input) DOUBLE PRECISION * The minimum pivot in the Sturm sequence. * * SPDIAM (input) DOUBLE PRECISION * The spectral diameter of the matrix. * * TWIST (input) INTEGER * The twist index for the twisted factorization that is used * for the negcount. * TWIST = N: Compute negcount from L D L^T - LAMBDA I = L+ D+ L * TWIST = 1: Compute negcount from L D L^T - LAMBDA I = U- D- U * TWIST = R: Compute negcount from L D L^T - LAMBDA I = N(r) D( * * INFO (output) INTEGER * Error flag. * * Further Details * =============== * * Based on contributions by * 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 * * ===================================================================== * * .. Parameters ..


Constructor Summary
SLARRB()
           
 
Method Summary
static void SLARRB(int n, float[] d, float[] lld, int ifirst, int ilast, float rtol1, float rtol2, int offset, float[] w, float[] wgap, float[] werr, float[] work, int[] iwork, float pivmin, float spdiam, int twist, intW info)
           
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

SLARRB

public SLARRB()
Method Detail

SLARRB

public static void SLARRB(int n,
                          float[] d,
                          float[] lld,
                          int ifirst,
                          int ilast,
                          float rtol1,
                          float rtol2,
                          int offset,
                          float[] w,
                          float[] wgap,
                          float[] werr,
                          float[] work,
                          int[] iwork,
                          float pivmin,
                          float spdiam,
                          int twist,
                          intW info)