Continuous Class Reference

Represents a variable in a continuous-time simulation. More...

Inheritance diagram for Continuous:

Collaboration diagram for Continuous:

Public Member Functions
	Continuous ()
	Constructs a new continuous-time variable linked to the default simulator, without initializing it.
	Continuous (Simulator sim)
	Constructs a new continuous-time variable linked to the given simulator, without initializing it. More...
void	init (double val)
	Initializes or reinitializes the continuous-time variable to val. More...
double	value ()
	Returns the current value of this continuous-time variable. More...
Simulator	simulator ()
	Returns the simulator linked to this continuous-time variable. More...
void	setSimulator (Simulator sim)
	Sets the simulator linked to this continuous-time variable. More...
void	startInteg ()
	Starts the integration process that will change the state of this variable at each integration step.
void	startInteg (double val)
	Same as startInteg, after initializing the variable to val. More...
void	stopInteg ()
	Stops the integration process for this continuous variable. More...
abstract double	derivative (double t)
	This method should return the derivative of this variable with respect to time, at time \(t\). More...
void	afterEachStep ()
	This method is executed after each integration step for this Continuous variable. More...

Static Public Member Functions
static void	selectEuler (double h)
	Selects the Euler method as the integration method, with the integration step size h, in time units, for the default simulator. More...
static void	selectRungeKutta4 (double h)
	Selects a Runge-Kutta method of order 4 as the integration method to be used, with step size h. More...
static void	selectRungeKutta2 (double h)
	Selects a Runge-Kutta method of order 2 as the integration method to be used, with step size h. More...

Package Attributes
boolean	active
double	value
Event	ev
double	phi
double	pi
double	buffer
double	sum

Detailed Description

Represents a variable in a continuous-time simulation.

This abstract class provides the basic structures and tools for continuous-time simulation, where certain variables evolve continuously in time, according to differential equations. Such continuous variables can be mixed with events and processes.

Each type of continuous-time variable should be defined as a subclass of Continuous. The instances of these subclasses are the actual continuous-time variables. Each subclass must implement the method derivative which returns its derivative with respect to time. The trajectory of this variable is determined by integrating this derivative. The subclass may also reimplement the method afterEachStep, which is executed immediately after each integration step. By default (in the class Continuous), this method does nothing. This method could, for example, verify if the variable has reached a given threshold, or update a graphical illustration of the variable trajectory.

When creating a class representing a continuous variable, the #toString method can be overridden to display information about the continuous variable. This information will be displayed when formating the event list as a string.

Each continuous variable has a linked simulator represented by an instance of the Simulator class. If no simulator is provided explicitly when constructing a variable, the default simulator returned by Simulator.getDefaultSimulator is used.

Constructor & Destructor Documentation

Continuous()

Continuous

(

Simulator

sim

)

Constructs a new continuous-time variable linked to the given simulator, without initializing it.

Parameters

sim	the simulator associated to this variable.

public Continuous (String name) \begin{hide} {
   this();
   this.name = name;
} \end{hide}

Constructs a new continuous-time variable (same as Continuous()) with name name and linked to the default simulator. This name can be used to identify the Continuous variable in traces and reports.

public Continuous (Simulator sim, String name) \begin{hide} {
   this(sim);
   this.name = name;
} \end{hide}

Constructs a new continuous-time variable (same as Continuous(sim)) with name name. This name can be used to identify the Continuous variable in traces and reports.

Member Function Documentation

afterEachStep()

void afterEachStep

(

)

This method is executed after each integration step for this Continuous variable.

Here, it does nothing, but every subclass of Continuous may reimplement it.

derivative()

abstract double derivative ( double  t )

abstract

This method should return the derivative of this variable with respect to time, at time \(t\).

Every subclass of Continuous that is to be instantiated must implement it. If the derivative does not depend explicitly on time, \(t\) becomes a dummy parameter. Internally, the method is used with \(t\) not necessarily equal to the current simulation time.

Parameters

t	time at which the derivative must be computed

init()

void init

(

double

val

)

Initializes or reinitializes the continuous-time variable to val.

Parameters

val	initial value of the variable

selectEuler()

static void selectEuler ( double  h )

static

Selects the Euler method as the integration method, with the integration step size h, in time units, for the default simulator.

The non-static method selectEuler in ContinuousState can be used to set the integration method for any given simulator. This method appears here only to keep compatibility with older versions of SSJ; using a non-static Simulator instance rather than the default simulator is recommended.

Parameters

h	integration step, in simulation time units

selectRungeKutta2()

static void selectRungeKutta2 ( double  h )

static

Selects a Runge-Kutta method of order 2 as the integration method to be used, with step size h.

The non-static method selectRungeKutta2 in ContinuousState can be used to set the integration method for any given simulator. This method appears here only to keep compatibility with older versions of SSJ; using a non-static Simulator instance rather than the default simulator is recommended.

selectRungeKutta4()

static void selectRungeKutta4 ( double  h )

static

Selects a Runge-Kutta method of order 4 as the integration method to be used, with step size h.

The non-static method selectRungeKutta4 in ContinuousState can be used to set the integration method for any given simulator. This method appears here only to keep compatibility with older versions of SSJ; using a non-static Simulator instance rather than the default simulator is recommended.

setSimulator()

void setSimulator

(

Simulator

sim

)

Sets the simulator linked to this continuous-time variable.

This method should not be called while this variable is active.

Parameters

sim	the simulator of the current variable

simulator()

Simulator simulator

(

)

Returns the simulator linked to this continuous-time variable.

Returns

the current simulator of the variable

startInteg()

void startInteg

(

double

val

)

Same as startInteg, after initializing the variable to val.

Parameters

val	initial value to start integration from

stopInteg()

void stopInteg

(

)

Stops the integration process for this continuous variable.

The variable keeps the value it took at the last integration step before calling stopInteg.

value()

double value

(

)

Returns the current value of this continuous-time variable.

Returns

the current value of the variable

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

• Continuous.java