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java.lang.Object umontreal.iro.lecuyer.simevents.Continuous
public abstract class Continuous
This abstract class provides the basic structures and tools for continuoustime 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 continuoustime variable should be defined as a
subclass of Continuous.
The instances of these subclasses are the actual continuoustime
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.
One of the methods selectEuler
, selectRungeKutta2
or
selectRungeKutta4
must be called before starting
any integration.
These methods permit one to select the numerical integration method
and the step size h (in time units) that will be used
for all continuoustime variables.
For all the methods, an integration step at time t changes
the values of the variables from their old values at time t  h to their
new values at time t.
Each integration step is scheduled as an event and added to the event list.
When creating a continuous variable class,
the toString
method can be overriden to display
information about the continuous variable. This information will
be displayed when formating the event list as a string.
Constructor Summary  

Continuous()
Constructs a new continuoustime variable, without initializing it. 
Method Summary  

void 
afterEachStep()
This method is executed after each integration step for this Continuous variable. 
abstract double 
derivative(double t)
This method should return the derivative of this variable with respect to time, at time t. 
void 
init(double val)
Initializes or reinitializes the continuoustime variable to val. 
static void 
selectEuler(double h)
Selects the Euler method as the integration method, with the integration step size h, in time units. 
static void 
selectRungeKutta2(double h)
Selects a RungeKutta method of order 2 as the integration method to be used, with step size h. 
static void 
selectRungeKutta4(double h)
Selects a RungeKutta method of order 4 as the integration method to be used, with step size h. 
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. 
void 
stopInteg()
Stops the integration process for this continuous variable. 
double 
value()
Returns the current value of this continuoustime variable. 
Methods inherited from class java.lang.Object 

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait 
Constructor Detail 

public Continuous()
Method Detail 

public void init(double val)
val
 initial value of the variablepublic double value()
public static void selectEuler(double h)
h
 integration step, in simulation time unitspublic static void selectRungeKutta2(double h)
h
 integration step, in simulation time unitspublic static void selectRungeKutta4(double h)
h
 integration step, in simulation time unitspublic void startInteg()
public void startInteg(double val)
startInteg
, after initializing the variable
to val.
val
 initial value to start integration frompublic void stopInteg()
public abstract double derivative(double t)
t
 time at which the derivative must be computedpublic void afterEachStep()

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