org.netlib.lapack
Class Slarrb

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

public class Slarrb
extends java.lang.Object

Following is the description from the original
Fortran source.  For each array argument, the Java
version will include an integer offset parameter, so
the arguments may not match the description exactly.
Contact seymour@cs.utk.edu with any questions.

* .. * * Purpose * ======= * * Given the relatively robust representation(RRR) L D L^T, SLARRB * 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) REAL array, dimension (N) * The n diagonal elements of the diagonal matrix D. * * L (input) REAL array, dimension (N-1) * The n-1 subdiagonal elements of the unit bidiagonal matrix L. * * LD (input) REAL array, dimension (N-1) * The n-1 elements L(i)*D(i). * * 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 in the cluster. * * ILAST (input) INTEGER * The index of the last eigenvalue in the cluster. * * SIGMA (input) REAL * The shift used to form L D L^T (see SLARRF). * * RELTOL (input) REAL * The relative tolerance. * * W (input/output) REAL 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) REAL array, dimension (N) * The gaps between the eigenvalues of L D L^T. Very small * gaps are changed on output. * * WERR (input/output) REAL 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) REAL 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
Slarrb()
           
 
Method Summary
static void slarrb(int n, float[] d, int _d_offset, float[] l, int _l_offset, float[] ld, int _ld_offset, float[] lld, int _lld_offset, int ifirst, int ilast, float sigma, float reltol, float[] w, int _w_offset, float[] wgap, int _wgap_offset, float[] werr, int _werr_offset, float[] work, int _work_offset, int[] iwork, int _iwork_offset, int 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,
                          int _d_offset,
                          float[] l,
                          int _l_offset,
                          float[] ld,
                          int _ld_offset,
                          float[] lld,
                          int _lld_offset,
                          int ifirst,
                          int ilast,
                          float sigma,
                          float reltol,
                          float[] w,
                          int _w_offset,
                          float[] wgap,
                          int _wgap_offset,
                          float[] werr,
                          int _werr_offset,
                          float[] work,
                          int _work_offset,
                          int[] iwork,
                          int _iwork_offset,
                          int info)