org.netlib.lapack
Class Slarrf

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

public class Slarrf
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 initial representation L D L^T and its cluster of close * eigenvalues (in a relative measure), W( CLSTRT ), W( CLSTRT+1 ), ... * W( CLEND ), SLARRF finds a new relatively robust representation * L D L^T - SIGMA I = L(+) D(+) L(+)^T such that at least one of the * eigenvalues of L(+) D(+) L(+)^T is relatively isolated. * * Arguments * ========= * * N (input) INTEGER * The order of the matrix (subblock, if the matrix splitted). * * 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). * * CLSTRT (input) INTEGER * The index of the first eigenvalue in the cluster. * * CLEND (input) INTEGER * The index of the last eigenvalue in the cluster. * * W (input) REAL array, dimension >= (CLEND-CLSTRT+1 * The eigenvalue APPROXIMATIONS of L D L^T in ascending order. * W( CLSTRT ) through W( CLEND ) form the cluster of relatively * close eigenalues. * * WGAP (input/output) REAL array, dimension >= (CLEND-C * The separation from the right neighbor eigenvalue in W. * * WERR (input) REAL array, dimension >= (CLEND-CLSTRT+1 * WERR contain the semiwidth of the uncertainty * interval of the corresponding eigenvalue APPROXIMATION in W * * SPDIAM (input) estimate of the spectral diameter obtained from the * Gerschgorin intervals * * CLGAPL, CLGAPR (input) absolute gap on each end of the cluster. * Set by the calling routine to protect against shifts too clos * to eigenvalues outside the cluster. * * PIVMIN (input) DOUBLE PRECISION * The minimum pivot allowed in the Sturm sequence. * * SIGMA (output) REAL * The shift used to form L(+) D(+) L(+)^T. * * DPLUS (output) REAL array, dimension (N) * The N diagonal elements of the diagonal matrix D(+). * * LPLUS (output) REAL array, dimension (N-1) * The first (N-1) elements of LPLUS contain the subdiagonal * elements of the unit bidiagonal matrix L(+). * * WORK (workspace) REAL array, dimension (2*N) * Workspace. * * 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
Slarrf()
           
 
Method Summary
static void slarrf(int n, float[] d, int _d_offset, float[] l, int _l_offset, float[] ld, int _ld_offset, int clstrt, int clend, float[] w, int _w_offset, float[] wgap, int _wgap_offset, float[] werr, int _werr_offset, float spdiam, float clgapl, float clgapr, float pivmin, floatW sigma, float[] dplus, int _dplus_offset, float[] lplus, int _lplus_offset, float[] work, int _work_offset, intW info)
           
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

Slarrf

public Slarrf()
Method Detail

slarrf

public static void slarrf(int n,
                          float[] d,
                          int _d_offset,
                          float[] l,
                          int _l_offset,
                          float[] ld,
                          int _ld_offset,
                          int clstrt,
                          int clend,
                          float[] w,
                          int _w_offset,
                          float[] wgap,
                          int _wgap_offset,
                          float[] werr,
                          int _werr_offset,
                          float spdiam,
                          float clgapl,
                          float clgapr,
                          float pivmin,
                          floatW sigma,
                          float[] dplus,
                          int _dplus_offset,
                          float[] lplus,
                          int _lplus_offset,
                          float[] work,
                          int _work_offset,
                          intW info)