org.netlib.lapack
Class DLAIC1

java.lang.Object
  org.netlib.lapack.DLAIC1

public class DLAIC1
extends java.lang.Object

DLAIC1 is a simplified interface to the JLAPACK routine dlaic1.
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
 *  =======
 *
 *  DLAIC1 applies one step of incremental condition estimation in
 *  its simplest version:
 *
 *  Let x, twonorm(x) = 1, be an approximate singular vector of an j-by-j
 *  lower triangular matrix L, such that
 *           twonorm(L*x) = sest
 *  Then DLAIC1 computes sestpr, s, c such that
 *  the vector
 *                  [ s*x ]
 *           xhat = [  c  ]
 *  is an approximate singular vector of
 *                  [ L     0  ]
 *           Lhat = [ w' gamma ]
 *  in the sense that
 *           twonorm(Lhat*xhat) = sestpr.
 *
 *  Depending on JOB, an estimate for the largest or smallest singular
 *  value is computed.
 *
 *  Note that [s c]' and sestpr**2 is an eigenpair of the system
 *
 *      diag(sest*sest, 0) + [alpha  gamma] * [ alpha ]
 *                                            [ gamma ]
 *
 *  where  alpha =  x'*w.
 *
 *  Arguments
 *  =========
 *
 *  JOB     (input) INTEGER
 *          = 1: an estimate for the largest singular value is computed.

 *          = 2: an estimate for the smallest singular value is computed.
 *
 *  J       (input) INTEGER
 *          Length of X and W
 *
 *  X       (input) DOUBLE PRECISION array, dimension (J)
 *          The j-vector x.
 *
 *  SEST    (input) DOUBLE PRECISION
 *          Estimated singular value of j by j matrix L
 *
 *  W       (input) DOUBLE PRECISION array, dimension (J)
 *          The j-vector w.
 *
 *  GAMMA   (input) DOUBLE PRECISION
 *          The diagonal element gamma.
 *
 *  SEDTPR  (output) DOUBLE PRECISION
 *          Estimated singular value of (j+1) by (j+1) matrix Lhat.
 *
 *  S       (output) DOUBLE PRECISION
 *          Sine needed in forming xhat.
 *
 *  C       (output) DOUBLE PRECISION
 *          Cosine needed in forming xhat.
 *
 *  =====================================================================
 *
 *     .. Parameters ..

Constructor Summary

DLAIC1()

Method Summary

static void

DLAIC1(int job, int j, double[] x, double sest, double[] w, double gamma, doubleW sestpr, doubleW s, doubleW c)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DLAIC1

public DLAIC1()

Method Detail

DLAIC1

public static void DLAIC1(int job,
                          int j,
                          double[] x,
                          double sest,
                          double[] w,
                          double gamma,
                          doubleW sestpr,
                          doubleW s,
                          doubleW c)