Class AbstractFieldODEDetector<T extends AbstractFieldODEDetector<T,E>,E extends CalculusFieldElement<E>>
- java.lang.Object
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- org.hipparchus.ode.events.AbstractFieldODEDetector<T,E>
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- Type Parameters:
T
- type of the detectorE
- type of the field elements
- All Implemented Interfaces:
FieldODEEventDetector<E>
- Direct Known Subclasses:
FieldEventSlopeFilter
public abstract class AbstractFieldODEDetector<T extends AbstractFieldODEDetector<T,E>,E extends CalculusFieldElement<E>> extends Object implements FieldODEEventDetector<E>
Base class for #@linkFieldODEEventDetector
.- Since:
- 3.0
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Field Summary
Fields Modifier and Type Field Description static int
DEFAULT_MAX_ITER
Default maximum number of iterations in the event time search.static double
DEFAULT_MAXCHECK
Default maximum checking interval (s).static double
DEFAULT_THRESHOLD
Default convergence threshold (s).
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Constructor Summary
Constructors Modifier Constructor Description protected
AbstractFieldODEDetector(FieldAdaptableInterval<E> maxCheck, int maxIter, BracketedRealFieldUnivariateSolver<E> solver, FieldODEEventHandler<E> handler)
Build a new instance.
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Method Summary
All Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description protected abstract T
create(FieldAdaptableInterval<E> newMaxCheck, int newMaxIter, BracketedRealFieldUnivariateSolver<E> newSolver, FieldODEEventHandler<E> newHandler)
Build a new instance.abstract E
g(FieldODEStateAndDerivative<E> s)
Compute the value of the switching function.FieldODEEventHandler<E>
getHandler()
Get the underlying event handler.FieldAdaptableInterval<E>
getMaxCheckInterval()
Get the maximal time interval between events handler checks.int
getMaxIterationCount()
Get the upper limit in the iteration count for event localization.BracketedRealFieldUnivariateSolver<E>
getSolver()
Get the root-finding algorithm to use to detect state events.void
init(FieldODEStateAndDerivative<E> s0, E t)
Initialize event handler at the start of an ODE integration.boolean
isForward()
Check if the current propagation is forward or backward.T
withHandler(FieldODEEventHandler<E> newHandler)
Setup the event handler to call at event occurrences.T
withMaxCheck(E newMaxCheck)
Setup the maximum checking interval.T
withMaxCheck(FieldAdaptableInterval<E> newMaxCheck)
Setup the maximum checking interval.T
withMaxIter(int newMaxIter)
Setup the maximum number of iterations in the event time search.T
withSolver(BracketedRealFieldUnivariateSolver<E> newSolver)
Setup the root-finding algorithm to use to detect state events.T
withThreshold(E newThreshold)
Setup the convergence threshold.
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Field Detail
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DEFAULT_MAXCHECK
public static final double DEFAULT_MAXCHECK
Default maximum checking interval (s).- See Also:
- Constant Field Values
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DEFAULT_THRESHOLD
public static final double DEFAULT_THRESHOLD
Default convergence threshold (s).- See Also:
- Constant Field Values
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DEFAULT_MAX_ITER
public static final int DEFAULT_MAX_ITER
Default maximum number of iterations in the event time search.- See Also:
- Constant Field Values
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Constructor Detail
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AbstractFieldODEDetector
protected AbstractFieldODEDetector(FieldAdaptableInterval<E> maxCheck, int maxIter, BracketedRealFieldUnivariateSolver<E> solver, FieldODEEventHandler<E> handler)
Build a new instance.- Parameters:
maxCheck
- maximum checking interval, must be strictly positive (s)maxIter
- maximum number of iterations in the event time searchsolver
- root-finding algorithm to use to detect state eventshandler
- event handler to call at event occurrences
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Method Detail
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init
public void init(FieldODEStateAndDerivative<E> s0, E t)
Initialize event handler at the start of an ODE integration.This method is called once at the start of the integration. It may be used by the event handler to initialize some internal data if needed.
The default implementation does nothing
This implementation sets the direction of integration and initializes the event handler. If a subclass overrides this method it should call
super.init(s0, t)
.- Specified by:
init
in interfaceFieldODEEventDetector<T extends AbstractFieldODEDetector<T,E>>
- Parameters:
s0
- initial time, state vector and derivativet
- target time for the integration
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g
public abstract E g(FieldODEStateAndDerivative<E> s)
Compute the value of the switching function.The discrete events are generated when the sign of this switching function changes. The integrator will take care to change the stepsize in such a way these events occur exactly at step boundaries. The switching function must be continuous in its roots neighborhood (but not necessarily smooth), as the integrator will need to find its roots to locate precisely the events.
Also note that the integrator expect that once an event has occurred, the sign of the switching function at the start of the next step (i.e. just after the event) is the opposite of the sign just before the event. This consistency between the steps must be preserved, otherwise
exceptions
related to root not being bracketed will occur.This need for consistency is sometimes tricky to achieve. A typical example is using an event to model a ball bouncing on the floor. The first idea to represent this would be to have
g(state) = h(state)
where h is the height above the floor at timestate.getTime()
. Wheng(state)
reaches 0, the ball is on the floor, so it should bounce and the typical way to do this is to reverse its vertical velocity. However, this would mean that before the eventg(state)
was decreasing from positive values to 0, and after the eventg(state)
would be increasing from 0 to positive values again. Consistency is broken here! The solution here is to haveg(state) = sign * h(state)
, where sign is a variable with initial value set to+1
. Each timeeventOccurred
method is called,sign
is reset to-sign
. This allows theg(state)
function to remain continuous (and even smooth) even across events, despiteh(state)
is not. Basically, the event is used to foldh(state)
at bounce points, andsign
is used to unfold it back, so the solvers sees ag(state)
function which behaves smoothly even across events.This method is idempotent, that is calling this multiple times with the same state will result in the same value, with two exceptions. First, the definition of the g function may change when an
event occurs
on the handler, as in the above example. Second, the definition of the g function may change when theevent occurs
method of any other event handler in the same integrator returnsAction.RESET_EVENTS
,Action.RESET_DERIVATIVES
, orAction.RESET_STATE
.- Specified by:
g
in interfaceFieldODEEventDetector<T extends AbstractFieldODEDetector<T,E>>
- Parameters:
s
- current value of the independent time variable, state vector and derivative- Returns:
- value of the g switching function
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getMaxCheckInterval
public FieldAdaptableInterval<E> getMaxCheckInterval()
Get the maximal time interval between events handler checks.- Specified by:
getMaxCheckInterval
in interfaceFieldODEEventDetector<T extends AbstractFieldODEDetector<T,E>>
- Returns:
- maximal time interval between events handler checks
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getMaxIterationCount
public int getMaxIterationCount()
Get the upper limit in the iteration count for event localization.- Specified by:
getMaxIterationCount
in interfaceFieldODEEventDetector<T extends AbstractFieldODEDetector<T,E>>
- Returns:
- upper limit in the iteration count for event localization
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getSolver
public BracketedRealFieldUnivariateSolver<E> getSolver()
Get the root-finding algorithm to use to detect state events.- Specified by:
getSolver
in interfaceFieldODEEventDetector<T extends AbstractFieldODEDetector<T,E>>
- Returns:
- root-finding algorithm to use to detect state events
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withMaxCheck
public T withMaxCheck(E newMaxCheck)
Setup the maximum checking interval.This will override a maximum checking interval if it has been configured previously.
- Parameters:
newMaxCheck
- maximum checking interval (s)- Returns:
- a new detector with updated configuration (the instance is not changed)
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withMaxCheck
public T withMaxCheck(FieldAdaptableInterval<E> newMaxCheck)
Setup the maximum checking interval.This will override a maximum checking interval if it has been configured previously.
- Parameters:
newMaxCheck
- maximum checking interval (s)- Returns:
- a new detector with updated configuration (the instance is not changed)
- Since:
- 3.0
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withMaxIter
public T withMaxIter(int newMaxIter)
Setup the maximum number of iterations in the event time search.This will override a number of iterations if it has been configured previously.
- Parameters:
newMaxIter
- maximum number of iterations in the event time search- Returns:
- a new detector with updated configuration (the instance is not changed)
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withThreshold
public T withThreshold(E newThreshold)
Setup the convergence threshold.This is equivalent to call
withSolver(new FieldBracketingNthOrderBrentSolver<>(zero, newThreshold, zero, 5)
, so it will override a solver if one has been configured previously.- Parameters:
newThreshold
- convergence threshold- Returns:
- a new detector with updated configuration (the instance is not changed)
- See Also:
withSolver(BracketedRealFieldUnivariateSolver)
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withSolver
public T withSolver(BracketedRealFieldUnivariateSolver<E> newSolver)
Setup the root-finding algorithm to use to detect state events.This will override a solver if it has been configured previously.
- Parameters:
newSolver
- root-finding algorithm to use to detect state events- Returns:
- a new detector with updated configuration (the instance is not changed)
- See Also:
withThreshold(CalculusFieldElement)
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withHandler
public T withHandler(FieldODEEventHandler<E> newHandler)
Setup the event handler to call at event occurrences.This will override a handler if it has been configured previously.
- Parameters:
newHandler
- event handler to call at event occurrences- Returns:
- a new detector with updated configuration (the instance is not changed)
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getHandler
public FieldODEEventHandler<E> getHandler()
Get the underlying event handler.- Specified by:
getHandler
in interfaceFieldODEEventDetector<T extends AbstractFieldODEDetector<T,E>>
- Returns:
- underlying event handler
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create
protected abstract T create(FieldAdaptableInterval<E> newMaxCheck, int newMaxIter, BracketedRealFieldUnivariateSolver<E> newSolver, FieldODEEventHandler<E> newHandler)
Build a new instance.- Parameters:
newMaxCheck
- maximum checking intervalnewMaxIter
- maximum number of iterations in the event time searchnewSolver
- root-finding algorithm to use to detect state eventsnewHandler
- event handler to call at event occurrences- Returns:
- a new instance of the appropriate sub-type
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isForward
public boolean isForward()
Check if the current propagation is forward or backward.- Returns:
- true if the current propagation is forward
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