I have fond memories of building an analog computer as a project from Popular Electronics that simulated a lunar lander mission. At reset you had fuel, altitude, horizontal and vertical velocity. Your input was an angle and a thrust knob (two potentiometers) and a comparative that latched when altitude reached 0 based on your velocities being less than 1m/s. It was tremendous fun to play but no graphics, just some mA meters to tell you your status.
Analog Computers
61–70 of 107 posts
Re: Analog Computers
#62At last, we will have a truly random number generator! Not the simulated fake rand() using timestamps as seed.
Most modern Intel and AMD CPUs have a truly random number generator, generated in a non-digital way.
Re: Analog Computers
#63A good summary of analog computers can be found on the wikipedia article: https://en.wikipedia.org/wiki/Analog_computer Takeaway: Analog computers are limited in precision and by "analog noise"; the precision of the components used determine the precision of the output. Usually no more than 3 or 4 decimal places are possible, at least with the tech that was used in their heydey. I would say that is still close to the…
Analog (or analogue) computers have their uses, however, in my experience, with analogue electronic computers, they have many problems:
- limited dynamic range of perhaps 30dB (1000)
- it is easy to saturate a signal (there is no overflow bit)
- oscillations are easy to induce, but once again hard to detect, especially in a circuit in the middle of a calculation chain
- noise gets amplified across the system
Re: Analog Computers
#64>The human brain is a great example – its processing power is estimated at about 38 petaflops, about two-fifths of that of TaihuLight. Huh? So we now have computers more powerful than the human brain? I thought that was still some decades off. And how would one even measure such a thing? In the apples-to-apples comparison, a stupid human trick floating-point calculation savant might manage 1 flop/s.
If you see an estimation of human brain computation power, it's probably best to assume it's nonsense. There are wildly different estimates, and as computers have gotten faster, the estimates seem to have risen, which suggests ego is involved.
Re: Analog Computers
#65I have fond memories of building an analog computer as a project from Popular Electronics that simulated a lunar lander mission. At reset you had fuel, altitude, horizontal and vertical velocity. Your input was an angle and a thrust knob (two potentiometers) and a comparative that latched when altitude reached 0 based on your velocities being less than 1m/s. It was tremendous fun to play but no graphics, just some mA…
Sounded cool, so searched for it. Page 41:
http://www.americanradiohistory.com/Archive-Elementary-Elect...
Re: Analog Computers
#66It's strange that the article does not mention anything about hydraulic macroeconomics and MONIAC, they were once widely used to verify theories in economics. https://en.wikipedia.org/wiki/MONIAC https://en.wikipedia.org/wiki/Hydraulic_macroeconomics
It's too bad MONIAC couldn't model the Stagflation of the 70's or it might be a useful model.
Re: Analog Computers
#67A good summary of analog computers can be found on the wikipedia article: https://en.wikipedia.org/wiki/Analog_computer Takeaway: Analog computers are limited in precision and by "analog noise"; the precision of the components used determine the precision of the output. Usually no more than 3 or 4 decimal places are possible, at least with the tech that was used in their heydey. I would say that is still close to the…
> Usually no more than 3 or 4 decimal places are possible By that do you mean accurate to 1 part in 100 (3dp) or 1000 (4dp) or what? Since the scale of a representation is arbitrary, I'm not sure what dp means here.
Kind of seems like if you are measuring the analog computers virility by the number of decimal places it can represent maybe you are mis-using the machine. I mean how many decimal places can you or I do in our head in real-time?
Re: Analog Computers
#68Earlier quoted context omitted.
What you're describing is generally accepted to be physically unrealizable. In fact, the sentence that follows your quoted sentence cites two commonly known physical limitations that prevent the existence of your "computational class above and beyond Turing". Whether or not there exist physically realizable computations that are not computable by a turing machine is an open question, but most physicists and computati…
Read unlimited as arbitrary precision. I'm familiar with the Turing thesis but he's wrong.
> I'm familiar with the Turing thesis but he's wrong.
Could you at least explain in what way you think he is wrong. Surely you must guess how participants on a programming forum will react to a statement like that.
Re: Analog Computers
#69Earlier quoted context omitted.
Read unlimited as arbitrary precision. I'm familiar with the Turing thesis but he's wrong.
> I'm familiar with the Turing thesis but he's wrong. Could you at least explain in what way you think he is wrong. Surely you must guess how participants on a programming forum will react to a statement like that.
The extended Turing-Church thesis states that an analog computer can be simulated on a Turing machine. It can but not efficiently.
Look into the work of Lenora Blum. She wrote a book "Complexity and Real computation".
Re: Analog Computers
#70A good summary of analog computers can be found on the wikipedia article: https://en.wikipedia.org/wiki/Analog_computer Takeaway: Analog computers are limited in precision and by "analog noise"; the precision of the components used determine the precision of the output. Usually no more than 3 or 4 decimal places are possible, at least with the tech that was used in their heydey. I would say that is still close to the…
Analog (or analogue) computers have their uses, however, in my experience, with analogue electronic computers, they have many problems: - limited dynamic range of perhaps 30dB (1000) - it is easy to saturate a signal (there is no overflow bit) - oscillations are easy to induce, but once again hard to detect, especially in a circuit in the middle of a calculation chain - noise gets amplified across the system
Reminded me of A.K. Dewdney's "Computer Recreations" column in "Scientific American" back in the day (I think a lot of people may have hated on his column since it followed in the shadow of Martin Gardener's infamous "Mathematical Recreations"). One of the "analog computers" he mentioned was using dried spaghetti to sort numbers — where the length of each spaghetti noodle represented the magnitude of a number. Of course grabbing them into a bundle in your hand and setting the bundle on end on a flat surface would "sort" the values.
Would the surface tension across a film that accurately finds the shortest path between n points be considered a "computation"?
One thing fascinating by "analog computers" is the way they seem to be practically instantaneous regardless of n. That is perhaps part of the efficiency reflected in the article.