RE: Re: dynamics: comment about MBdyn...

On Tue, 15 Jul 2003, Tiller, Michael (M.M.) wrote:

[... various questions about the meaning of some terminology...]
> > Can you elaborate on this a bit more, please?
[...]
> Does that help?
Absolutely! I think I now fully understand what you mean. (And I
agree.)

BTW, a search on the web gave two possible candidates to start from as
a DAE solver evironment. (I am not quite sure about the licenses
though.. )

 <http://yoric.mit.edu/daepack/intro/intro.html>
 <http://www.control.lth.se/~cace/omsimrefman.html>

[...]
> > I think the existence of FSM and events in Modelica are enough to cope
> > with all these "hybrid" things.
> 
> Hybrid in what sense now?!?  
Both senses! I think they really are the same thing (at least
conceptually): changing a discrete variable corresponds to a change in
"state" (with "state" nicely defined as "behaviour of the implementation
of an interface" in Software Pattern contexts).

> As I mentioned, changes in connectivity or
> causality are beyond the scope of the Modelica semantics.
Yes. But there is interest in adding these things, as far as I can
tell.

> > within INRIA that is keeping all their software from being 
> > open source...)
> 
> I think Modelica is a good model for this.  Establish an independent body to
> define the interfaces and perhaps a reference implementation and then Scilab
> can build on that (rather than being the developers of it).

We are again talking about different things: I want an open source
"solver", while you mention an "open source interface" :-) And Scilab
is not free software, although they say it is...  I quote from their
license.txt file:
- "Any commercial use or circulation of the DERIVED SOFTWARE shall
   have been previously authorized by INRIA and ENPC."
- Any changes can only be distributed as patches.

Herman

-- 
  K.U.Leuven, Mechanical Engineering, Robotics Research Group
<http://people.mech.kuleuven.ac.be/~bruyninc> Tel: +32 16 322480