Package org.orekit.utils

Class ParameterDriver

java.lang.Object

org.orekit.utils.ParameterDriver

Direct Known Subclasses:

ParameterDriversList.DelegatingDriver

public class ParameterDriver
extends Object

Class allowing to drive the value of a parameter.

This class is typically used as a bridge between an estimation algorithm (typically orbit determination or optimizer) and an internal parameter in a physical model that needs to be tuned, or a bridge between a finite differences algorithm and an internal parameter in a physical model that needs to be slightly offset. The physical model will expose to the algorithm a set of instances of this class so the algorithm can call the setValue(double) method to update the parameter value. Each time the value is set, the physical model will be notified as it will register a ParameterObserver for this purpose.

This design has two major goals. First, it allows an external algorithm to drive internal parameters almost anonymously, as it only needs to get a list of instances of this class, without knowing what they really drive. Second, it allows the physical model to not expose directly setters methods for its parameters. In order to be able to modify the parameter value, the algorithm must retrieve a parameter driver.

Since:

8.0

Author:

Luc Maisonobe

See Also:

ParameterObserver

Constructor Summary

Constructors

Constructor	Description
ParameterDriver(String name, double referenceValue, double scale, double minValue, double maxValue)	Simple constructor.

Method Summary

Modifier and Type	Method	Description
void	addObserver(ParameterObserver observer)	Add an observer for this driver.
double	getMaxValue()	Get maximum parameter value.
double	getMinValue()	Get minimum parameter value.
String	getName()	Get name.
double	getNormalizedValue()	Get normalized value.
List<ParameterObserver>	getObservers()	Get the observers for this driver.
AbsoluteDate	getReferenceDate()	Get current reference date.
double	getReferenceValue()	Get reference parameter value.
double	getScale()	Get scale.
double	getValue()	Get current parameter value.
org.hipparchus.analysis.differentiation.DerivativeStructure	getValue(org.hipparchus.analysis.differentiation.DSFactory factory, Map<String,Integer> indices)	Get the value as a derivative structure.
boolean	isSelected()	Check if parameter is selected.
void	removeObserver(ParameterObserver observer)	Remove an observer.
void	setMaxValue(double maxValue)	Set maximum parameter value.
void	setMinValue(double minValue)	Set minimum parameter value.
void	setName(String name)	Change the name of this parameter driver.
void	setNormalizedValue(double normalized)	Set normalized value.
void	setReferenceDate(AbsoluteDate newReferenceDate)	Set reference date.
void	setReferenceValue(double referenceValue)	Set reference parameter value.
void	setScale(double scale)	Set scale.
void	setSelected(boolean selected)	Configure a parameter selection status.
void	setValue(double newValue)	Set parameter value.
String	toString()	Get a text representation of the parameter.

Methods inherited from class java.lang.Object

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

Constructor Detail

ParameterDriver

public ParameterDriver(String name,
                       double referenceValue,
                       double scale,
                       double minValue,
                       double maxValue)

Simple constructor.

At construction, the parameter is configured as not selected, the reference date is set to null and the value is set to the referenceValue.

Parameters:

name - name of the parameter

referenceValue - reference value of the parameter

scale - scaling factor to convert the parameters value to non-dimensional (typically set to the expected standard deviation of the parameter), it must be non-zero

minValue - minimum value

maxValue - maximum value

Method Detail

addObserver

public void addObserver(ParameterObserver observer)

Add an observer for this driver.

The observer valueChanged method is called once automatically when the observer is added, and then called at each value change.

Parameters:

observer - observer to add while being updated

removeObserver

public void removeObserver(ParameterObserver observer)

Remove an observer.

Parameters:

observer - observer to remove

Since:

9.1

getObservers

public List<ParameterObserver> getObservers()

Get the observers for this driver.

Returns:

an unmodifiable view of the observers for this driver

Since:

9.1

setName

public void setName(String name)

Change the name of this parameter driver.

Parameters:

name - new name

getName

public String getName()

Get name.

Returns:

name

getReferenceValue

public double getReferenceValue()

Get reference parameter value.

Returns:

reference parameter value

setReferenceValue

public void setReferenceValue(double referenceValue)

Set reference parameter value.

Parameters:

referenceValue - the reference value to set.

Since:

9.3

getMinValue

public double getMinValue()

Get minimum parameter value.

Returns:

minimum parameter value

setMinValue

public void setMinValue(double minValue)

Set minimum parameter value.

Parameters:

minValue - the minimum value to set.

Since:

9.3

getMaxValue

public double getMaxValue()

Get maximum parameter value.

Returns:

maximum parameter value

setMaxValue

public void setMaxValue(double maxValue)

Set maximum parameter value.

Parameters:

maxValue - the maximum value to set.

Since:

9.3

getScale

public double getScale()

Get scale.

Returns:

scale

setScale

public void setScale(double scale)

Set scale.

Parameters:

scale - the scale to set.

Since:

9.3

getNormalizedValue

public double getNormalizedValue()

Get normalized value.

The normalized value is a non-dimensional value suitable for use as part of a vector in an optimization process. It is computed as (current - reference)/scale.

Returns:

normalized value

setNormalizedValue

public void setNormalizedValue(double normalized)

Set normalized value.

The normalized value is a non-dimensional value suitable for use as part of a vector in an optimization process. It is computed as (current - reference)/scale.

Parameters:

normalized - value

getReferenceDate

public AbsoluteDate getReferenceDate()

Get current reference date.

Returns:

current reference date (null if it was never set)

Since:

9.0

setReferenceDate

public void setReferenceDate(AbsoluteDate newReferenceDate)

Set reference date.

Parameters:

newReferenceDate - new reference date

Since:

9.0

getValue

public double getValue()

Get current parameter value.

Returns:

current parameter value

getValue

public org.hipparchus.analysis.differentiation.DerivativeStructure getValue(org.hipparchus.analysis.differentiation.DSFactory factory,
                                                                            Map<String,Integer> indices)

Get the value as a derivative structure.

Parameters:

factory - factory for the derivatives

indices - indices of the differentiation parameters in derivatives computations

Returns:

value with derivatives

Since:

9.3

setValue

public void setValue(double newValue)

Set parameter value.

If newValue is below getMinValue(), it will be silently set to getMinValue(). If newValue is above getMaxValue(), it will be silently set to getMaxValue().

Parameters:

newValue - new value

setSelected

public void setSelected(boolean selected)

Configure a parameter selection status.

Selection is used for estimated parameters in orbit determination, or to compute the Jacobian matrix in partial derivatives computation.

Parameters:

selected - if true the parameter is selected, otherwise it will be fixed

isSelected

public boolean isSelected()

Check if parameter is selected.

Selection is used for estimated parameters in orbit determination, or to compute the Jacobian matrix in partial derivatives computation.

Returns:

true if parameter is selected, false if it is not

toString

public String toString()

Get a text representation of the parameter.

Overrides:

toString in class Object

Returns:

text representation of the parameter, in the form name = value.