Defines an interface for an asymmetric Gaussian image model based on the model_image class. This is an explicit example of a model_image object. More...

#include "model/model_image_asymmetric_gaussian.h"

Inheritance diagram for model_image_asymmetric_gaussian:

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Collaboration diagram for model_image_asymmetric_gaussian:

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Public Member Functions
void	use_numerical_visibilities ()
	State switch to select numerically computed visibilities using the machinery in model_image. Once called, all future visibilities will be computed numerically until use_analytical_visibilities() is called.

void	use_analytical_visibilities ()
	State switch to select analytically computed visibilities using the the analytical Fourier transform of the Gaussian. Once called, all future visibilities will be computed analytically until use_numerical_visibilities() is called.

virtual size_t	size () const
	A user-supplied function that returns the number of the parameters the model expects.

virtual std::complex< double >	visibility (datum_visibility &d, double accuracy)
	Returns complex visibility in Jy computed from the image given a datum_visibility_amplitude object, containing all of the accoutrements. While this provides access to the actual data value, the two could be separated if necessary. Also takes an accuracy parameter with the same units as the data, indicating the accuracy with which the model must generate a comparison value. Note that this can be redefined in child classes.

virtual double	visibility_amplitude (datum_visibility_amplitude &d, double acc)
	Returns visibility ampitudes in Jy computed from the image given a datum_visibility_amplitude object, containing all of the accoutrements. While this provides access to the actual data value, the two could be separated if necessary. Also takes an accuracy parameter with the same units as the data, indicating the accuracy with which the model must generate a comparison value. Note that this is redefined to accomodate the possibility of using the analytical computation.

virtual double	closure_phase (datum_closure_phase &d, double acc)
	Returns closure phase in degrees computed from the image given a datum_closure_phase object, containing all of the accoutrements. While this provides access to the actual data value, the two could be separated if necessary. Also takes an accuracy parameter with the same units as the data, indicating the accuracy with which the model must generate a comparison value. Note that this is redefined since the closure phase of Gaussian images is identically zero.

virtual double	closure_amplitude (datum_closure_amplitude &d, double acc)
	Returns closure amplitude computed from the image given a datum_closure_phase object, containing all of the accoutrements. While this provides access to the actual data value, the two could be separated if necessary. Also takes an accuracy parameter with the same units as the data, indicating the accuracy with which the model must generate a comparison value. Note that this can be redefined in child classes.

virtual std::string	model_tag () const
	Return a string that contains a unique identifying tag for use with the ThemisPy plotting features.

Public Member Functions inherited from model_image
virtual void	generate_model (std::vector< double > parameters)
	A one-time generate function that permits model construction prior to calling the visibility_amplitude, closure_phase, etc. for each datum. Takes a vector of parameters.

virtual void	generate_complex_visibilities ()
	A one-time generate function that will generate the complex visibilities and store them. This must be called after generate_model has been called.

void	output_image (std::string fname, bool rotate=false)

void	get_image (std::vector< std::vector< double > > &alpha, std::vector< std::vector< double > > &beta, std::vector< std::vector< double > > &I) const
	Provides direct access to the constructed image. Sets a 2D grid of angles (alpha, beta) in radians and intensities in Jy per steradian.

void	get_visibilities (std::vector< std::vector< double > > &u, std::vector< std::vector< double > > &v, std::vector< std::vector< std::complex< double > > > &V) const
	Provides direct access to the complex visibilities. Sets a 2D grid of baselines (u,v) in lambda, and visibilites in Jy.

void	get_visibility_amplitudes (std::vector< std::vector< double > > &u, std::vector< std::vector< double > > &v, std::vector< std::vector< double > > &V) const
	Provides direct access to the visibility amplitudes. Sets a 2D grid of baselines (u,v) in lambda, and visibilites in Jy.

void	use_spline_interp (bool use_spline)
	Provides ability to use bicubic spline interpolator (true) instead of regular bicubic. Code defaults to false.

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.

void	write_model_tag_file (std::string tagfilename="model_image.tag") const
	Write a unique identifying tag for use with the ThemisPy plotting features. This calls the overloaded version with the outstream, which is the only function that need be rewritten in child classes.

virtual void	write_model_tag_file (std::ofstream &tagout) const
	Write a unique identifying tag for use with the ThemisPy plotting features. For most child classes, the default implementation is suffcient. However, should that not be the case, this is the only function that need be rewritten in child classes.

Private Member Functions
virtual void	generate_image (std::vector< double > parameters, std::vector< std::vector< double > > &I, std::vector< std::vector< double > > &alpha, std::vector< std::vector< double > > &beta)
	Generates and returns rectalinear grid of intensities associated with the Gaussian image model in Jy/str located at pixels centered on angular positions alpha and beta, both specified in radians and aligned with a fiducial direction. Note that the parameter vector has had the position removed.

Private Attributes
double	_Itotal
	Internal total intensity.

double	_sigma_alpha
	Std. dev. in fiducial horizontal direction.

double	_sigma_beta
	Std. dev. in fiducial vertical direction.

bool	_use_analytical_visibilities
	If true uses analytical visibility computation, if false use numerical visibilities.

Additional Inherited Members
Protected Attributes inherited from model_image
MPI_Comm	_comm

bool	_generated_model
	True when a model is generated with generate_model.

bool	_generated_visibilities
	True when model visibilities have been computed.

bool	_use_spline
	True when want to use bicubic spline interpolator.

double	_position_angle
	Position angle of the image, assumed to be the last element of the parameter list passed to generate_model. Assumed to be in radians and defined E of N.

std::vector< double >	_current_parameters
	Last set of parameters passed to generate_image, useful to determine if it is necessary to recompute the model. Useful, e.g., if we are varying only position angle, or if recomputing for a number of different data sets at the same set of parameters.

std::vector< std::vector< double > >	_alpha
	2D grid of horizonal pixel locations in radians, relative to the fiducial direction of the image (i.e., unrotated by the position angle).

std::vector< std::vector< double > >	_beta
	2D grid of vertical pixel locations in radians, relative to the fiducial direction of the image (i.e., unrotated by the position angle).

std::vector< std::vector< double > >	_I
	2D grid of intensities at pixel locations in Jy/str.

Protected Attributes inherited from model_visibility
MPI_Comm	_comm

Protected Attributes inherited from model_visibility_amplitude
MPI_Comm	_comm

Protected Attributes inherited from model_closure_phase
MPI_Comm	_comm

Protected Attributes inherited from model_closure_amplitude
MPI_Comm	_comm

Detailed Description

The Gaussian image is defined by the parameters in Broderick et al. (2011): an overall flux normalization, a measure of the total standard deviation, a measure of the asymmetry, and the position angle (removed from the end of the parameter list by model_image.generate() prior to passing to model_image_asymmetric_gaussian.generate_image().)

Parameter list:

parameters[0] ... Total, integrated flux in Jy.
parameters[1] ... \( \sigma = \sqrt{2} \sigma_m \sigma_M / \left( \sigma_M^2 + \sigma_m^2 \right)^{1/2} \)
parameters[2] ... \( A = (\sigma_M^2-\sigma_m^2)/(\sigma_M^2+\sigma_m^2) \)
parameters[3] ... Position angle (in model_image) in radians

Warning
Note that the two size parameters are not the semimajor and semiminor axes, leading to a natural degeneracy between swapping the axes sizes and rotating the image by pi/2 radians.

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

model/model_image_asymmetric_gaussian.h
model/model_image_asymmetric_gaussian.cpp

Public Member Functions

Private Member Functions

Private Attributes

Additional Inherited Members

Detailed Description