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

Method Summary

Modifier and Type	Method and 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.
AbsoluteDate	getReferenceDate() Get current reference date.
double	getReferenceValue() Get reference parameter value.
double	getScale() Get scale.
double	getValue() Get current parameter value.
boolean	isSelected() Check if parameter is selected.
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	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)
                throws OrekitException

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

Throws:

OrekitException - if scale is too close to zero

Method Detail

addObserver

public void addObserver(ParameterObserver observer)
                 throws OrekitException

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

Throws:

OrekitException - if the observer triggers one while being updated

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

getMinValue

public double getMinValue()

Get minimum parameter value.

Returns:

minimum parameter value

getMaxValue

public double getMaxValue()

Get maximum parameter value.

Returns:

maximum parameter value

getScale

public double getScale()

Get scale.

Returns:

scale

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)
                        throws OrekitException

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

Throws:

OrekitException - if an observer throws one

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

setValue

public void setValue(double newValue)
              throws OrekitException

Set parameter value.

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

Parameters:

newValue - new value

Throws:

OrekitException - if an observer throws one

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.