Given a coupled DEVS model, simulation algorithms are methods to generate the model's legal behaviors, which are a set of trajectories not to reach illegal states. (see
[Zeigler84]
originally introduced the algorithms that handle time variables related to lifespan and elapsed time by introducing two other time variables, last event time, , and next event time with the following relations:
and
where denotes the current time. And the remaining time,
is equivalently computed as
apparently .
Based on these relationships, the algorithms to simulate the behavior of a given Coupled DEVS are written as follows.
Algorithm
algorithm DEVS-coordinator
Variables:
parent // parent coordinator
: // time of last event
: // time of next event
// the associated Coupled DEVS model
when receive init-message(Time t)
for eachdo
send init-message(t) to child ;
;
when receive star-message(Time t)
ifthen
error: bad synchronization;
send star-message(t)to ;
;
when receive x-message(, Time t)
if and == false then
error: bad synchronization;
for eachdo
send x-message(,t) to child ;
;
when receive y-message(, Time t)
for eachdo
send x-message(,t) to child ifthen
send y-message(, t) to parent;
;
;