org.netlib.lapack
Class DLASD4
java.lang.Object
org.netlib.lapack.DLASD4
public class DLASD4
 extends java.lang.Object
DLASD4 is a simplified interface to the JLAPACK routine dlasd4.
This interface converts Javastyle 2D rowmajor arrays into
the 1D columnmajor 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
* =======
*
* This subroutine computes the square root of the Ith updated
* eigenvalue of a positive symmetric rankone 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 rankone 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 jth
* 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 Ith updated eigenvalue.
*
* WORK (workspace) DOUBLE PRECISION array, dimension ( N )
* If N .ne. 1, WORK contains (D(j) + sigma_I) in its jth
* 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 (originati?) 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 (switchfor3poles?) 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
* RenCang Li, Computer Science Division, University of California
* at Berkeley, USA
*
* =====================================================================
*
* .. Parameters ..
Method Summary 
static void 
DLASD4(int n,
int i,
double[] d,
double[] z,
double[] delta,
double rho,
doubleW sigma,
double[] work,
intW info)

Methods inherited from class java.lang.Object 
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait 
DLASD4
public DLASD4()
DLASD4
public static void DLASD4(int n,
int i,
double[] d,
double[] z,
double[] delta,
double rho,
doubleW sigma,
double[] work,
intW info)