likelihood_closure_amplitude Class Reference

Defines a class that constructs a closure amplitude likelihood object. More...

#include "likelihood/likelihood_closure_amplitude.h"

Inheritance diagram for likelihood_closure_amplitude:

Collaboration diagram for likelihood_closure_amplitude:

Public Member Functions
	likelihood_closure_amplitude (data_closure_amplitude &data, model_closure_amplitude &model)
virtual double	operator() (std::vector< double > &x)
	Returns the log-likelihood of a vector of parameters \( \mathbf{x} \).
virtual double	chi_squared (std::vector< double > &x)
	Returns the \( \chi^2 \) of a vector of parameters \( \mathbf{x} \).
virtual void	set_mpi_communicator (MPI_Comm comm)
	Defines a set of processors provided to the model for parallel computation via an MPI communicator. Only facilates code parallelization if the model computation is parallelized via MPI.
Public Member Functions inherited from likelihood_base
virtual std::vector< double >	gradient (std::vector< double > &x, prior &Pr)
void	output_model_data_comparison (std::ostream &out)
void	output_model_data_comparison (std::string filename)

Protected Member Functions
virtual void	output (std::ostream &out)

Private Attributes
data_closure_amplitude &	_data
model_closure_amplitude &	_model

Additional Inherited Members
Protected Attributes inherited from likelihood_base
MPI_Comm	_comm

Detailed Description

This class takes a closure amplitude data object and a closure amplitude model object, and then returns the log likelihood. by direct comparison to the observational data assuming that the measured visibility amplitudes has a Gaussian quotient distribution. This is a good approximation at large SNRs ( \(\ge4\)) and for closure amplitudes constructed such that they are \(\le1\). Note that doing so is always possible; however, this is not performed during likelihood evaluation.

Currently assumes that the ratio of the combined thermal errors of the terms in numerator and denominator is unity. This can be relaxed in the future, exploiting the known SEFDs of the stations involved in the closure phase.

This class also includes an utility function for estimating the \( \chi^2 = -2 \mathcal{L} \) to assess fit quality. This is approximately the normal \( \chi^2 \), i.e., similar to order unity.

Member Function Documentation

void output ( std::ostream &  out )

protectedvirtual

Outputs the data and model, as modified by the likelihood appropriately, to the specified output stream. Useful for comparison later.

Reimplemented from likelihood_base.

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The documentation for this class was generated from the following files:

• likelihood/likelihood_closure_amplitude.h
• likelihood/likelihood_closure_amplitude.cpp