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From: The Natural Philosopher <tnp@invalid.invalid>
Newsgroups: comp.os.linux.advocacy,comp.os.linux.misc
Subject: Re: Rewriting SSA. Is This A Chance For GNU/Linux?
Date: Sun, 6 Apr 2025 12:55:48 +0100
Organization: A little, after lunch
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On 06/04/2025 05:26, c186282 wrote:
> On 4/5/25 9:07 PM, The Natural Philosopher wrote:
     temperature conditions that add errors in.
>>
>> Not really, That was mostly sorted years ago.
> 
> 
>    Ummm ... I'm gonna kinda have to disagree.
> 
>    There are several factors that lead to errors in
>    analog electronics - simple temperature being
>    the worst.
> 

Not really. If you se as close to zero coefficient resistors and enough 
feedback the circuits  are insensitive to temperature.
In terms of using junctions to do multiplication, there are ways of 
compensating for temperature in one device using the same effect in 
another, and on chip they are thermally coupled and doped the same. So 
it works very well indeed
> 
>>>    Keep
>>>    carrying those errors through several stages and soon
>>>    all you have is error, pretending to be The Solution.
>>
>> So no different from floating point based current climate models, then...
> 
> 
>    Digital FP *can* be done to almost arbitrary precision.
>    If you're running, say, a climate or 'dark energy' model
>    then you use a LOT of precision.
> 

And get a very accurate 'wrong answer'.

The problem is the time it takes to do it.


> 
>>>    Again, perhaps some meta-material that's NOT sensitive
>>>    to what typically throws-off analog electronics MIGHT
>>>    be made.
>>>
>>>    I'm trying to visualize what it would take to make
>>>    an all-analog version of, say, a payroll spreadsheet :-)
>>>
>> An awful lot of op-amps.
> 
> 
>    To say the least :-)
> 
>    CAN be done, but is it WORTH it ???
> 
>    But, I suppose, a whole-budget CAN be viewed
>    as an analog equation IF you try hard enough.
> 

Most complex dynamic systems are 'analogue' and anyone who has modelled 
them using analogue electronics can tell you that if they do not have 
the right negative feedback they become unstable, and that's how we 
engineers know that 'positive feedback' in the climate is bullshit.
What you can do with a multitude of opamps resistors and capacitors is 
to model extremely complex dynamic systems very quickly, and look for 
instability or unexpected results.

No one does it any more, because everyoine fell in love with digital, 
but there are times when it works better.

> 
>> The thing is that analogue computers were useful for system analysis 
>> years before digital stuff came along. You could examine a dynamic 
>> system and see if it was stable or not.
> 
>    Well, *how* stable it is ........
> 
>    Digital is always right-on.
> 
No, it isn't.

>    So what do you NEED most - speed or accuracy ?
> 
>> If not you did it another way. People who dribble on about 'climate 
>> tipping points'have no clue really as to how real life complex 
>> analogue systems work.
> 
>    I'm just gonna say that "climate" is beyond ANY kind
>    of models - analog OR digital. TOO many butterflies.
> 
That is the point.
There are chaotic elements but its *bounded* chaos.  I looked everywhere 
for mathematical papers to try and determine the criteria for a chaotic 
system to become bounded, or even to identify how many strange 
attractors there were, or where they were located.

No one has done the work.

And yet digital climate modelling cannot even represent the past, let 
alone the future.



>>>    Now discrete use of analog as, as you suggested, doing
>>>    multiplication/division/logs initiated and read by
>>>    digital ... ?
>>>
>> Its being thought about.
> 
>    And we shall see ... advantage, or not ?
> 

In certain cases it is a better solution. I can envisage a chip 
comprised of many many linear amplifiers whose gain, frequency response 
and interconnections were programmable by digital logic, to allow one to 
model an enormously interconnected system very quickly, to at least see 
what its sensitive areas in fact were....

I.e. identify the butterflies...


>    Maybe, horrors, "depends" .....
> 
Well that means nothing. That's just anti-tech speak for 'I don't know 
what I am talking about, and I am as good as you. so therefore you don't 
either'...

>    The "real world" acts as a very complex analog
>    equation - until you get down to quantum levels.
>    HOW the hell to best DEAL with that ???
> 
The point is you don't.  If your system is so unstable that one atomic 
decay renders the cat dead, it doesn't last long in the 'real world

The real world is *conservative*. It consists of systems that have 
*temporal persistence*. They have 'stood the test of time', if you like.

If your model - be it analogue or digital - doesn't have the right sort 
of feedback to do that, its clearly not an accurate model is it?


>>>    Oh well, we're out in sci-fi land with most of this ...
>>>    may as well talk about using giant evil brains in
>>>    jars as computers  :-)
>>>
>> Well no, we are not.
>> Digital traded speed for precision.
> 
> 
>    I'd say digital traded precision for speed ...
> 
No. Digital is SLOW. Many hundreds of cycles to do in what analogue can 
do *approximately* in one or two.

>> Massive parallelisation will definitely do *some* things faster.
> 
>    Agreed ... but not EVERYTHING.
> 
>    Sometimes there's just no substitute for clock
>    speed and high-speed mem access.
> 

Well tough, because you aint gonna get that . The speed of light is the 
speed of light
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