CTBaseIntegrator
ptolemy.domains.ct.kernel.CTBaseIntegrator

The base class for integrators in the continuous-time (CT) domain. An integrator has one input port and one output port. Conceptually, the input is the derivative of the output w.r.t. time. So an ordinary differential equation (ODE) dx/dt = f(x, t) can be built by:

 
               +---------------+
 
        dx/dt  |               |   x
 
    +--------->|   Integrator  |---------+----->
 
    |          |               |         |
 
    |          +---------------+         |
 
    |                                    |
 
    |             |---------|            |
 
    +-------------| f(x, t) |<-----------+
 
                  |---------|
 

An integrator is a dynamic actor that can emit a token (a state) at a time without knowing the input at that time. An integrator is a step size control actor that can control the accuracy of the ODE solution by adjusting step sizes. An integrator has memory, which is its state.

To help solving the ODE, a set of internal variables are used:
state: This is the value of the state variable at a time point, which has beed confirmed by all the step size control actors. tentative state: This is the value of the state variable which has not been confirmed. It is a starting point for other actors to estimate the accuracy of this integration step. history: The previous states and their derivatives. History may be used by multistep integration methods.

For different ODE solving methods, the functionality of an integrator may be different. The delegation and strategy design patterns are used in this class, basic abstract ODESolver class, and the concrete ODE solver classes. Some solver-dependent methods of integrators delegate to the concrete ODE solvers.

An integrator has one parameter: the initialState. At the initialization stage of the simulation, the state of the integrator is set to the initial state. Changes of the initialState made during execution cause the state to be reset to the specified value. The default value of the parameter is 0.0 of type double.

An integrator can possibly have several auxiliary variables for the the ODE solvers to use. The number of the auxiliary variables is checked before each iteration. The ODE solver class provides the number of variables needed for that particular solver. The auxiliary variables can be set and get by setAuxVariables() and getAuxVariables() methods.

Author(s): Jie Liu, Haiyang Zheng
Version:$Id: CTBaseIntegrator.java,v 1.123 2006/03/28 23:58:20 cxh Exp $
Pt.Proposed Rating:Yellow (hyzheng)
Pt.Accepted Rating:Red (yuhong)


input
The input port. This is a single port of type double.

output
The output port. This is a single port of type double.



initialState
The initial state of type DoubleToken. The default value is 0.0.