[SystemSafety] Modelling and coding guidelines: "Unambiguous Graphical Representation"

[Mike Ellims]

>> Except that semantics of MathLab/Simulink is very fragile, e.g. order 
>> of execution of state machines on a diagram depends on the order they
were drawn.

> Yep.

You can get around this issue by explicitly defining the execution order by
assigning block priorities, but you have to know to do it.


-----Original Message-----
From: systemsafety
[mailto:systemsafety-bounces at lists.techfak.uni-bielefeld.de] On Behalf Of
Peter Bernard Ladkin
Sent: 26 February 2016 11:35
To: systemsafety at lists.techfak.uni-bielefeld.de
Subject: Re: [SystemSafety] Modelling and coding guidelines: "Unambiguous
Graphical Representation"



On 2016-02-26 10:33 , David MENTRE wrote:
> Le 26/02/2016 09:43, Peter Bernard Ladkin a écrit :
>> Another reason is the prevelance of MathLab/Simulink in this domain. 
>> Simulink is now an executable specification language. Since there is 
>> one supplier, it is de facto unambiguous (there is just one 
>> simulator, so the single meaning of a Simulink spec is precisely what
that simulator does with the spec).
> 
> Some people have even formally defined the semantics of Simulink or a
subset of it:

I think what this says is that some people have interpreted in a formal way
what they think Simulink diagrams should ideally mean. Whether they do mean
that or not is another question.

It's laudable, but it's a long way from what "formally defined the semantics
of Simulink" would mean to practicing engineers. That would further entail
that (a) one of those semantics had been independently assessed as adequate,
(b) MathWorks had accepted it, and (c) MathWorks had demonstrated that their
simulator (the execution engine for Simulink) conformed to the semantics.

> Except that semantics of MathLab/Simulink is very fragile, e.g. order 
> of execution of state machines on a diagram depends on the order they were
drawn.

Yep.

PBL

Prof. Peter Bernard Ladkin, Faculty of Technology, University of Bielefeld,
33594 Bielefeld, Germany Je suis Charlie
Tel+msg +49 (0)521 880 7319  www.rvs.uni-bielefeld.de







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