org.netlib.lapack
Class Dlasd4

java.lang.Object
  org.netlib.lapack.Dlasd4

public class Dlasd4
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
 *  =======
 *
 *  This subroutine computes the square root of the I-th updated
 *  eigenvalue of a positive symmetric rank-one modification to
 *  a positive diagonal matrix whose entries are given as the squares
 *  of the corresponding entries in the array d, and that
 *
 *         0 <= D(i) < D(j)  for  i < j
 *
 *  and that RHO > 0. This is arranged by the calling routine, and is
 *  no loss in generality.  The rank-one modified system is thus
 *
 *         diag( D ) * diag( D ) +  RHO *  Z * Z_transpose.
 *
 *  where we assume the Euclidean norm of Z is 1.
 *
 *  The method consists of approximating the rational functions in the
 *  secular equation by simpler interpolating rational functions.
 *
 *  Arguments
 *  =========
 *
 *  N      (input) INTEGER
 *         The length of all arrays.
 *
 *  I      (input) INTEGER
 *         The index of the eigenvalue to be computed.  1 <= I <= N.
 *
 *  D      (input) DOUBLE PRECISION array, dimension ( N )
 *         The original eigenvalues.  It is assumed that they are in
 *         order, 0 <= D(I) < D(J)  for I < J.
 *
 *  Z      (input) DOUBLE PRECISION array, dimension ( N )
 *         The components of the updating vector.
 *
 *  DELTA  (output) DOUBLE PRECISION array, dimension ( N )
 *         If N .ne. 1, DELTA contains (D(j) - sigma_I) in its  j-th
 *         component.  If N = 1, then DELTA(1) = 1.  The vector DELTA
 *         contains the information necessary to construct the
 *         (singular) eigenvectors.
 *
 *  RHO    (input) DOUBLE PRECISION
 *         The scalar in the symmetric updating formula.
 *
 *  SIGMA  (output) DOUBLE PRECISION
 *         The computed lambda_I, the I-th updated eigenvalue.
 *
 *  WORK   (workspace) DOUBLE PRECISION array, dimension ( N )
 *         If N .ne. 1, WORK contains (D(j) + sigma_I) in its  j-th
 *         component.  If N = 1, then WORK( 1 ) = 1.
 *
 *  INFO   (output) INTEGER
 *         = 0:  successful exit
 *         > 0:  if INFO = 1, the updating process failed.
 *
 *  Internal Parameters
 *  ===================
 *
 *  Logical variable ORGATI (origin-at-i?) is used for distinguishing
 *  whether D(i) or D(i+1) is treated as the origin.
 *
 *            ORGATI = .true.    origin at i
 *            ORGATI = .false.   origin at i+1
 *
 *  Logical variable SWTCH3 (switch-for-3-poles?) is for noting
 *  if we are working with THREE poles!
 *
 *  MAXIT is the maximum number of iterations allowed for each
 *  eigenvalue.
 *
 *  Further Details
 *  ===============
 *
 *  Based on contributions by
 *     Ren-Cang Li, Computer Science Division, University of California
 *     at Berkeley, USA
 *
 *  =====================================================================
 *
 *     .. Parameters ..

Constructor Summary

Dlasd4()

Method Summary

static void

dlasd4(int n, int i, double[] d, int _d_offset, double[] z, int _z_offset, double[] delta, int _delta_offset, double rho, doubleW sigma, double[] 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

Dlasd4

public Dlasd4()

Method Detail

dlasd4

public static void dlasd4(int n,
                          int i,
                          double[] d,
                          int _d_offset,
                          double[] z,
                          int _z_offset,
                          double[] delta,
                          int _delta_offset,
                          double rho,
                          doubleW sigma,
                          double[] work,
                          int _work_offset,
                          intW info)