xal.extension.twissobserver

Class CsZeroCurrentEstimator

java.lang.Object

xal.extension.twissobserver.CourantSnyderEstimator

xal.extension.twissobserver.CsZeroCurrentEstimator

public class CsZeroCurrentEstimator
extends CourantSnyderEstimator

Reconstructs the zero-current second-order beam moments from multiple profile data measurements along a beamline. This class is a simple extension of the TwissObjserverBase class providing only public access to the tools for computing the recursion function in the case of zero beam current.

Since:

Apr 18, 2013

Field Summary

Fields inherited from class xal.extension.twissobserver.CourantSnyderEstimator

bolDebug, dblConvErr, dblResErr, fmtMatrix, genTransMat, matCurrF, matCurrSigma

Constructor Summary

Constructors

Constructor and Description
CsZeroCurrentEstimator(boolean bolDebug, TransferMatrixGenerator genTransMat) Creates a new instance of ZeroCurrentSolution.
CsZeroCurrentEstimator(TransferMatrixGenerator genTransMatrix) Creates a new instance of ZeroCurrentSolution.

Method Summary

Modifier and Type	Method and Description
CovarianceMatrix	computeReconstruction(java.lang.String strRecDevId, java.util.ArrayList<Measurement> arrData) Computes the covariance matrix σ of Courant-Snyder parameters from the given data at the given device location.
CovarianceMatrix	computeReconstruction(java.lang.String strRecDevId, double dblBnchFreq, double dblBmCurr, java.util.ArrayList<Measurement> arrMsmts) Fulfills the requirement of the base class abstract function.

Methods inherited from class xal.extension.twissobserver.CourantSnyderEstimator

computeConvergenceError, computeObservationMatrix, computeObservationMatrix, computeReconFunction, computeReconSubFunction, computeResidualError, computeZeroCurrReconFunction, getReconConvergenceError, getReconResidualError, getReconstruction, isDebuggingOn, setDebug

Methods inherited from class java.lang.Object

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

Constructor Detail

CsZeroCurrentEstimator

public CsZeroCurrentEstimator(TransferMatrixGenerator genTransMatrix)

Creates a new instance of ZeroCurrentSolution.

Parameters:

genTransMat - a pre-configured transfer matrix engine used internally.

Since:

Apr 18, 2013

CsZeroCurrentEstimator

public CsZeroCurrentEstimator(boolean bolDebug,
                              TransferMatrixGenerator genTransMat)

Creates a new instance of ZeroCurrentSolution.

Parameters:

bolDebug - output debug information to the console if true

genTransMat - a pre-configured transfer matrix engine used internally.

Since:

Apr 18, 2013

Method Detail

computeReconstruction

public CovarianceMatrix computeReconstruction(java.lang.String strRecDevId,
                                              java.util.ArrayList<Measurement> arrData)
                                       throws ModelException

Computes the covariance matrix σ of Courant-Snyder parameters from the given data at the given device location. This is a least-squares reconstruction of the CS parameters using the given data. This is the set of second-order moments of the beam distribution. Since the measurement data cannot show coupling between phase planes, the covariance matrix is block diagonal where the 2×2 blocks correspond to each independent phase plane (see CorrelationMatrix). If the measurement data is zero for any phase plane, then the diagonal block corresponding to that phase plane is also zero.

The second-order moments are computed from and observation matrix which, in the zero current case, is independent of the initial state of the beam. The observation matrix relates the initial state (described by the second moments) to the observed quantities, in this case the measurement data of RMS beam sizes. For each phase plane: In the case were there are more data points than there are variables (i.e., greater than 3) then the returned solution is the least-squares solution; specifically, the set of moments that hits the most data. In the case where there are less data points than variables (i.e., less than 3) then the returned solution is the minimum norm (or "least energy") solution; specifically, the solution that has the smallest Lebesgue 2-norm. If we have 3 data points for the phase plane then the unique solution is returned.

NOTE

· If the reconstruction device has non-zero length the location of the moments corresponds to the exit of the device.

Parameters:

strRecDevId - ID of the device where the reconstruction is performed

arrData - measurement data consisting of RMS beam sizes

Returns:

block diagonal covariance matrix containing second-order moments at the reconstruction location

Throws:

ModelException - error occurred during the transfer matrix computations

Since:

Aug 31, 2012

computeReconstruction

public CovarianceMatrix computeReconstruction(java.lang.String strRecDevId,
                                              double dblBnchFreq,
                                              double dblBmCurr,
                                              java.util.ArrayList<Measurement> arrMsmts)
                                       throws ModelException

Fulfills the requirement of the base class abstract function. The beam charge parameter is ignored. This method is simply a proxy to computeReconstruction(String, ArrayList).

Specified by:

computeReconstruction in class CourantSnyderEstimator

Parameters:

strRecDevId - ID of the device where the reconstruction is performed

dblBnchFreq - bunch arrival frequency - Ignored

dblBmCurr - beam current - Ignored

arrData - measurement data consisting of RMS beam sizes

Returns:

block diagonal covariance matrix containing second-order moments at the reconstruction location

Throws:

ModelException - error occurred during the transfer matrix computations

Since:

May 1, 2013