Re: OT?: AF 447 and avionics software

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Tue, 9 Jun 2009 23:11:22 -0700 (PDT), MRE wrote:

> On 7 Jun., 15:19, "Dmitry A. Kazakov" <mail...@dmitry-kazakov.de>
> wrote:
>> On Sun, 07 Jun 2009 13:16:14 +0200, Florian Weimer wrote:
>>> * Dmitry A. Kazakov:
>>
>>>> Analogue systems are continuous, whatever complexity a continuous
>>>> system has it stay to some extent predictable.
>>
>>> Even if you've got resonance effects?
>>
>> Yes. An oscillation does it with finite mass and energy The acceleration is
>> limited, which is another way to say that it is continuous.
>>
>> In a discrete computing system a huge number of states are "equidistant".
>> You pay the same "price" for incrementing a register by one and for
>> resetting the CPU. This allows you to make great things - you can "travel"
>> to anywhere you want in very few steps - but this also makes the trajectory
>> so unpredictable.
>>
> For a single system Dimitry may be right. If however we talk about a
> network of
> analog systems (which we have in flight controls), the result of a
> malfunction
> is as unpredictable as for a similar digital system. Thanks to chaos-
> theory ;-)

Well, no. A chaotic trajectory is still continuous. Chaos theory is not
really as "unpredictable". A case comparable to digital systems would be
systems deploying nanotechnology, they should [mis]behave much alike.

P.S. I don't advocate for analogue systems. Once I saw the square root
module of an analogue computer. It was about 0.5x0.5x0.5 meter size. I
doubt that thing could fly. (:-))

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de