Dynamic Dataflow Modeling in Ptolemy II - Ptolemy Project ...

4 Application Examples
This section gives several examples to show how conditionals, data-dependent iterations,
recursion and other dynamic constructs can be modeled in DDF domain.
4.1 An OrderedMerge example
The first example in Figure 4.1 is due to Kahn and MacQueen. It calculates integers
whose prime factors are only 2, 3 and 5, with no redundancies. It uses the OrderedMerge
actor, which takes two monotonically increasing input sequences and merges them into
one monotonically increasing output sequence. This model was originally implemented
in PN domain and is adapted here to show the concept of an iteration in DDF domain.
Although no static or quasi-static schedule can be computed for this model, by adding a
requiredFiringsPerIteration parameter to Display actor and setting its value to one, we
have effectively defined one iteration of this model such that there is one output per
iteration. This iteration does not bring the model to its original state or anything close to
that, but matches well with our intuition and serves to precisely control the progress of
the simulation by specifying the number of iterations (i.,e. how many output tokens) we
want in one execution.
50