agi.foundation.celestial

(agi.foundation.models-2024r2.jar)

Class ClassicalEquationOfEquinoxes

java.lang.Object

agi.foundation.infrastructure.DefinitionalObject

agi.foundation.celestial.EquationOfEquinoxes

agi.foundation.celestial.ClassicalEquationOfEquinoxes

All Implemented Interfaces:

ICloneWithContext, IEnumerateDependencies, IEquatableDefinition, IFreezable

public final class ClassicalEquationOfEquinoxes
extends EquationOfEquinoxes

Represents the classical equation of the equinox as defined in the Explanatory Supplement to the Astronomical Almanac. This equation has been in use for many decades. For the updated equation of equinoxes defined by the IERS in 1996, see IersTechnicalNote21. To apply this equation of equinoxes, replace the existing EquationOfEquinoxes (get / set) with an instance of this class.

This class uses the existing NutationModel (get / set) and PrecessionModel (get / set).

Constructor Summary

Constructors

Constructor and Description
ClassicalEquationOfEquinoxes() Initializes a new instance.

Method Summary

Modifier and Type	Method and Description
protected boolean	checkForSameDefinition(EquationOfEquinoxes other) Checks to determine if another instance has the same definition as this instance and returns true if it does.
Object	clone(CopyContext context) Clones this object using the specified context.
protected int	computeCurrentDefinitionHashCode() Computes a hash code based on the current properties of this object.
MotionEvaluator1<Double>	getEquationOfTheEquinoxesEvaluator(EvaluatorGroup group) Gets an evaluator to compute the equation of the equinoxes.

Methods inherited from class agi.foundation.celestial.EquationOfEquinoxes

checkForSameDefinition, getEquationOfTheEquinoxesEvaluator

Methods inherited from class agi.foundation.infrastructure.DefinitionalObject

areSameDefinition, areSameDefinition, areSameDefinition, areSameDefinition, areSameDefinition, collectionItemsAreSameDefinition, collectionItemsAreSameDefinition, collectionItemsAreSameDefinition, dictionaryItemsAreSameDefinition, enumerateDependencies, freeze, freezeAggregatedObjects, getCollectionHashCode, getCollectionHashCode, getCollectionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDictionaryHashCode, getIsFrozen, isSameDefinition, throwIfFrozen

Methods inherited from class java.lang.Object

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

Constructor Detail

ClassicalEquationOfEquinoxes

public ClassicalEquationOfEquinoxes()

Initializes a new instance.

Method Detail

clone

public Object clone(CopyContext context)

Clones this object using the specified context.

This method should be implemented to call a copy constructor on the class of the object being cloned. The copy constructor should take the CopyContext as a parameter in addition to the existing instance to copy. The copy constructor should first call CopyContext.addObjectMapping(T, T) to identify the newly constructed instance as a copy of the existing instance. It should then copy all fields, using CopyContext.updateReference(T) to copy any reference fields.

A typical implementation of ICloneWithContext:

public static class MyClass implements ICloneWithContext {
    public MyClass(MyClass existingInstance, CopyContext context) {
        context.addObjectMapping(existingInstance, this);
        someReference = context.updateReference(existingInstance.someReference);
    }

    @Override
    public final Object clone(CopyContext context) {
        return new MyClass(this, context);
    }

    private Object someReference;
}

In general, all fields that are reference types should be copied with a call to CopyContext.updateReference(T). There are a couple of exceptions:

1. Fields that are aggregate parts of the object should always be copied. A referenced object is an aggregate if properties or methods on the object being copied can modify the externally-visible value of the referenced object.
2. If the semantics of the referenced object require that it have a single parent, owner, context, etc., and the object being copied is that parent, owner, or context, then the referenced object should always be copied.

If one of these exceptions applies, the CopyContext should be given an opportunity to update the reference before the reference is copied explicitly. Use CopyContext.updateReference(T) to update the reference. If CopyContext.updateReference(T) returns the original object, indicating that the context does not have a replacement registered, then copy the object manually by invoking a Clone method, a copy constructor, or by manually constructing a new instance and copying the values.

alwaysCopy = context.updateReference(existingInstance.alwaysCopy);
if (existingInstance.alwaysCopy != null && alwaysCopy == existingInstance.alwaysCopy) {
    alwaysCopy = (AlwaysCopy) existingInstance.alwaysCopy.clone(context);
}

If you are implementing an evaluator (a class that implements IEvaluator), the IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) method shares some responsibilities with the copy context constructor. Code duplication can be avoided by doing the following:

1. For references to other evaluators ONLY, simply assign the reference in the constructor instead of calling CopyContext.updateReference(T). You should still call CopyContext.updateReference(T) on any references to non-evaluators.
2. Call IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) as the last line in the constructor and pass it the same CopyContext passed to the constructor.
3. Implement IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) as normal. See the reference documentation for IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) for more information on implementing that method.

public MyClass(MyClass existingInstance, CopyContext context) {
    super(existingInstance, context);
    someReference = context.updateReference(existingInstance.someReference);
    evaluatorReference = existingInstance.evaluatorReference;
    updateEvaluatorReferences(context);
}

@Override
public void updateEvaluatorReferences(CopyContext context) {
    evaluatorReference = context.updateReference(evaluatorReference);
}

@Override
public Object clone(CopyContext context) {
    return new MyClass(this, context);
}

private Object someReference;
private IEvaluator evaluatorReference;

Specified by:

clone in interface ICloneWithContext

Specified by:

clone in class DefinitionalObject

Parameters:

context - The context to use to perform the copy.

Returns:

A new instance which is a copy of this object.

checkForSameDefinition

protected boolean checkForSameDefinition(EquationOfEquinoxes other)

Checks to determine if another instance has the same definition as this instance and returns true if it does. Derived classes MUST override this method and check all new fields introduced by the derived class for definitional equivalence. It is NOT necessary to check base class fields because the base class will already have done that. When overriding this method, you should NOT call the base implementation because it will return false for all derived-class instances. Derived classes should check the type of other to preserve the symmetric nature of IEquatableDefinition.isSameDefinition(java.lang.Object).

Specified by:

checkForSameDefinition in class EquationOfEquinoxes

Parameters:

other - The other instance to compare to this one.

Returns:

true if the two objects are defined equivalently; otherwise false.

computeCurrentDefinitionHashCode

protected int computeCurrentDefinitionHashCode()

Computes a hash code based on the current properties of this object. Derived classes MUST override this method and compute a hash code that combines: a unique hash code seed, the base implementation result, and the hash codes of all new fields introduced by the derived class which are used in the ClassicalEquationOfEquinoxes.checkForSameDefinition(agi.foundation.celestial.EquationOfEquinoxes) method.

Overrides:

computeCurrentDefinitionHashCode in class EquationOfEquinoxes

Returns:

The computed hash code.

getEquationOfTheEquinoxesEvaluator

public MotionEvaluator1<Double> getEquationOfTheEquinoxesEvaluator(EvaluatorGroup group)

Gets an evaluator to compute the equation of the equinoxes.

The result of evaluating will be a Motion<double> which represents the value of the equation of the equinoxes representing the offset between the mean and apparent equinoxes at the given JulianDate. No derivatives are provided.

The equation of the equinox uses a NutationModel and PrecessionModel defined by the instance of EarthCentralBody in the CentralBodiesFacet of the CalculationContext.

Specified by:

getEquationOfTheEquinoxesEvaluator in class EquationOfEquinoxes

Parameters:

group - The group with which to associate the new evaluator. By grouping evaluators that are often evaluated at the same Julian dates, common computations can be performed only once for the entire group instead of multiple times for each evaluator.

Returns:

An evaluator that evaluates the equation of the equinoxes.