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Class org.netlib.lapack.DLAED4

java.lang.Object
   |
   +----org.netlib.lapack.DLAED4

public class DLAED4

extends Object

DLAED4 is a simplified interface to the JLAPACK routine dlaed4.
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
 *  =======
 *
 *  This subroutine computes the I-th updated eigenvalue of a symmetric
 *  rank-one modification to a diagonal matrix whose elements are
 *  given in the array d, and that
 *
 *             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 )  +  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, 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) - lambda_I) in its  j-th
 *         component.  If N = 1, then DELTA(1) = 1.  The vector DELTA
 *         contains the information necessary to construct the
 *         eigenvectors.
 *
 *  RHO    (input) DOUBLE PRECISION
 *         The scalar in the symmetric updating formula.
 *
 *  DLAM   (output) DOUBLE PRECISION
 *         The computed lambda_I, the I-th updated eigenvalue.
 *
 *  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.
 *
 *  =====================================================================
 *
 *     .. Parameters ..

DLAED4()

DLAED4(int, int, double[], double[], double[], double, doubleW, intW)

 public DLAED4()

 public static void DLAED4(int n,
                           int i,
                           double d[],
                           double z[],
                           double delta[],
                           double rho,
                           doubleW dlam,
                           intW info)

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