Sacrificing Accuracy For Speed and Efficiency In Processors

Skudd writes "Modern computing has always been reliant on accuracy and correct answers. Now, a professor at Rice University in Houston posits that some future applications could be revolutionized by 'probabilistic computing.' Quoting: 'This afternoon, Krishna Palem, speaking at a computer science meeting in San Francisco, will announce results of the first real-world test of his probabilistic computer chip: The chip, which thrives on random errors, ran seven times faster than today's best technology while using just 1/30th the electricity. ... The high density of transistors on existing chips also leads to a lot of background "noise." To compensate, engineers increase the voltage applied to computer circuits to overpower the noise and ensure precise calculations. Palem began wondering how much a slight reduction in the quality of calculations might improve speed and save energy. He soon realized that some information was more valuable than other information. For example, in calculating a bank balance of $13,000.81, getting the "13" correct is much more important than the "81." Producing an answer of $13,000.57 is much closer to being correct than $57,000.81. While Palem's technology may not have a future in calculating missions to Mars, it probably has one in such applications as streaming music and video on mobile devices, he said.'

Comments

Bank balance

[johnny cashed]

And $81,000.31 is a much more correct answer!

Re:Bank balance

[CastrTroy]

I agree. The whole problem with the example given in the summary is that your bank balance should never be wrong. There is no room for error in calculating bank balances. I also don't want to hear skips and pops in my music because they though it would be more energy efficient to use a processor that produced errors. I already get 26 hours of charge out of my MP3 player. I'd rather have them focus on getting more space for cheaper so I can carry lossless audio on my portable mp3 player.

Re:Bank balance

[BadAnalogyGuy]

If you are listening to music on a portable media device, it's safe to say that you aren't going to be able to hear the difference between the lossy format and the lossless format.

It's like drinking from a well. Connoisseurs may claim to be able to taste the difference between it and tap water, but that's just the extra tang from all the bull shit.

Re:Bank balance

[moderatorrater]

I disagree. Cents is already an arbitrary cut off for the calculations' accuracy, why not just cut it off at dollars? I do my budget religiously every night and go over everything with my wife a couple of times a month. If every transaction were rounded up to the nearest dollar, it wouldn't destroy my finances. I doubt it would seriously mess up my finances if they were off by $5. Now, if I were able to give up efficiency and accuracy in my financial calculations for something else that I considered valuable (for instance, lower interest in my mortgage or my credit card payments counted for 30x what they did before), then this is something that should seriously be considered.

With regards to music, they're not talking about skips and pops, they're talking about extremely slight modulations in pitch or, in the case of video, a very slight difference in color. If these differences are random and small enough (say, 300 per second), then it averages out to the same thing and our minds can't tell the difference. Hell, if the differences are small enough you wouldn't really notice them anyway. If I could get 30x the battery life out of my laptop by accepting imperfections in the video it displays and in the audio it plays (and I know it wouldn't, but this is a hypothetical), then I'd gladly go for it.

Re:Bank balance

[phoenix321]

High accuracy is required for encoding music and video, though.

Maybe we could have a selective accuracy, where programmers can set their needs via registers or direct it to different CPU cores. Accurate cores for banking transactions, AV-stream encoding and 2D GUI operations while inaccurate cores are used for AV-stream decoding, and computer game 3d drawing and AI decisions.

There's a whole lot we are calculating now without the need for more than 3 significant digits - and a whole bunch where we intentionally use random numbers, sometimes even with strong hardware entropy gathering.

These are all cases where we could just scrap the accuracy for faster processing or longer battery times. No one cares about single bit errors in portable audio decoders or in high fps 3d gaming.

Re:Bank balance

[Hojima]

There are countless applications for a computer that don't depend on accuracy, but do depend on speed. For example: gaming, stock analysis, scientific/mathematical research etc. Just about every use for the computer can benefit from this. Bear in mind these applications can take the hit of inaccuracy, if not benefit from it depending on the situation. Yes there are some instances were accuracy is crucial, but that's why they will continue to make both of the processors. It's what they call a free market, and there will be always be a new niche to fill.

Re:Bank balance

[ZombieWomble]

Obviously this is the potential argument for these chips, but the majority of these systems have a trade-off between between speed and accuracy: Most numerical mathematical methods have a clear trade-off between speed and accuracy. It's pointless to gain speed if it pulls your accuracy down more than simply reducing the complexity of your algorithms.

Given that, I would expect this hardware - if it proves useful - would primarily be in the "entertainment" sector of the market. Of course making this judgment is pretty much impossible at the moment as there's no real information on just how bad the accuracy loss is with these chips.

Re:Bank balance

[memco]

Ok, so not only do I have to give up efficiency in the chip itself, but now my efficiency suffers because I now have to determine which chips are useful for which applications. I don't want to have to start thinking about whether or not I plan to use my new laptop for anything requiring accuracy greater than such and such a percentage. I suppose this might be effective for niche markets, but it seems messy if you try to make it part of all computing platforms.

Re:Bank balance

[Tuoqui]

Well the odds are you probably wouldn't even notice if a few bits here and there were wrong in your audio stream. I'm not sure what the error rate is but if its less than 17 times as much as we have now it'd be worth considering for some applications

I figure if they do use this technology they'd more than likely use the multi-core system currently in place and make one a high accuracy CPU while the other 2-4 cores high speed CPUs. Like someone said it'd be used for gaming and streaming video/audio where 'accuracy' isnt as important.

Re:Bank balance

[wik]

There's rounding in virtually every transaction you already encounter. Do you live in a location with sales tax?

In pay periods where my paycheck is mathematically supposed to be consistent, it also fluctuates by a cent sometimes. The value averages out but there's still rounding and it's quite obvious.

Re:Bank balance

[mdarksbane]

There are a few areas where games care a little bit about accuracy. You've got to be really careful about it in any kind of flight game with playing fields of more than a few miles in size. It's amazing the kind of graphical artifacts you can get if you don't take the error in floating points into account when you handle that sort of thing. In our first naive implementation of the engine, at around 50 kilometers out every character would jitter constantly every time they moved because of the last floating point bits being inaccurate.

Re:Bank balance

[shaitand]

'It's like drinking from a well. Connoisseurs may claim to be able to taste the difference between it and tap water, but that's just the extra tang from all the bull shit.'

Probably not the best example. Humans have an amazing ability to taste very minute differences in water. My TDS meter tells me that tap water here is extremely pure to begin with, but I can pick the same that has undergone carbon and ro filtering versus straight tap water in a blind taste test with 100% accuracy. I'm certainly no connoisseur.

Actually, I'm from rural Illinois, and all the water be it tap or properly maintained well is fairly sweet there with minimal filtering. Actually the streams there are a bit muddy tasting but the water itself is sweet as it flows. It definitely beats this Florida swap water. I tasted unfiltered Florida well water once (most Florida wells have filters built in) and I vomited. The tap water here won't make you sick and it isn't that nasty but it still tastes funky.

That said, I doubt I could tell the difference between tap, well, Illinois, or Florida water that has had that additional filtering (Carbon and Reverse Osmosis, any of those machines for $0.39/gallon at the grocery store will do). My TDS meter shows a difference in purity even from one dispensing machine to the next, but I can't taste that difference. Whatever minerals survive that process are probably pretty much the same anywhere and taste good. That filtered water tastes better than any of the unfiltered waters.

Re:Bank balance

[shaitand]

Don't forget there are errors in the hardware processes anyway and error correction algorithms running on the software side that take care of them.

Re:Bank balance

[ZombieWomble]

I don't think any of these things particularly benefit from this type of processor. All of the situations you describe involve some degree of randomness, but this CPU doesn't sound like a source of useful random values at all.

The randomness in these processes occurs in particular places, in particular quantities - this processor presumably produces some characteristic amount of randomness in each calculation, but the odds on it being a meaningful amount for whatever arbitrary calculation you're doing is vanishingly small - and given it's apparently treated to give different amounts of randomness in different bits, it's almost certainly non-uniform as well.

In almost all simulations you want to make use of extremely well-controlled random numbers - something which adding some noise as part of your floating-point calculations is not.

Re:Bank balance

[wisty]

Accuracy might not matter for some steps in an implicit, iterative numerical scheme.

Re:Bank balance

[Firethorn]

In all probability this would never make it into usage as a CPU, more likely a dedicated section of silicon performing the function of a GPU/FPU/DSP. Actual control instructions would be high-integrity, just the low significance digits would get the 'cheap but a bit more unreliable' methods.

I'd like to see how much an image would change if you imposed a 1% chance of a 10% error in either the chroma or luminance of each pixel. I'm willing to bet it'd be 'take a magnifying glass and the images next to each other to tell'. Change it to 30-60 hz video, and the perception of differences would go away.

Re:Bank balance

[Pseudonym]

Think about a computation such as X - Y. If X and Y have the 3 first same digit, then you will have 0 significant bit for the result.

Any numeric analyst worth their pay will have thought hard about every calculation. If there's a subtraction, then either it won't be two floating-point numbers of similar magnitude, or the result won't be crucial (e.g. it might be an error estimate rather than the actual result).

If the characteristics of the hardware are known, then algorithms can be designed to suit them. This is just another tool in the toolbox.

if you do anything more complicated than adding and multiplying, then you need accurate computation.

Because, of course, IEEE-754 floating point numbers are renowned for their accuracy.

Re:Bank balance

[arminw]

... In the US cents in my checkbook are important....

Would that not depend on whether the errors made were equally in your favor and against it? If you did a large number of transactions and half of them added a penny or two to your account and half of them subtracted a similar amount, it would all even out in the, would it not? Only if the errors were unidirectional, would there be a problem in the long term.

Re:Bank balance

[ozphx]

You wha?

I think hardware and software designers already have that covered when they perform processing on different parts of your system, such as your CPU, or GPU...

Specialization is a good thing, unless you have a preference for the performance of the directx reference rasterizer....

Re:Bank balance

[Profane MuthaFucka]

I don't think I agree. This processor could bring more lifelike movies to my house, for less money. I'm guessing that with this chip popping and rattling, I could get rid of the guy I hired to cough loudy and fumble with crinkly bags of chips in my "true movie experience" home theater room.

Re:Bank balance

[durrr]

Inaccurate = my darts miss the target by up to a meter.
Random = my darts may be assigned any possible movement vector with equal probability.

Please understand that there's a difference between these two. If i'm inaccurate we can compensate by altering the mechanics of our 'game'(make a huge dartboard, triangulate from multiple throws). Whereas if i'm random we can't really do much to help.

Accuracy(or lack of it) is not very challenging to measure either, and once you have it measured it should be trivial to compensate until the rate of significant errors drop lower than the chance of you being hit by lightning or whatever is considered within safe bounds.

You should consider that you could spend 85% of your cpu cycles on error corrections to achive equality with precision circuits while keeping the advantage of having 1/30 power cost. The advantage of 1/30 the powercost doesn't only(or neccesarily) translate to smaller utility bills. It also means less heat, which doesn't only mean less nosiy fans but also bigger, more powerful chips(with noisy fans). Scale your current cpu with 10x the amount of transistors at current tech and your computer will rival your microwave in heating power. At 1/30th the power that would still only be 1/3 of what you're already using.

Saying this technology will have no use at all is a bit unimaginative, unless you perhaps have a lot of stocks in the current industry?

Reminds me of...

[rob1980]

Q: Why didn't Intel call the Pentium the 586?
A: Because they added 486 and 100 on the first Pentium and got 585.999983605.

Re:Reminds me of...

[machine321]

My computer's not slow, it's just being careful.

Accuracy with financial calculations.

[onion2k]

Accuracy with financial calculations is extremely important. Hasn't this guy ever watched Superman 3?

Re:Accuracy with financial calculations.

[Briareos]

Hasn't this guy ever watched Superman 3?

Maybe he just watched Office Space and missed the whole Superman 3 reference?

np: Fennesz - Vacuum (Black Sea)

Re:Accuracy with financial calculations.

[Firethorn]

quite correct the thousands is far more important than the cents, however 13,810.00 is really close to 13,000.81 right. it has all the same numbers in a similar order.

Not by the fuzzy logic the guy's using. He's going for scientific accuracy. IE 13,000.81 (+-.001%). It's just our brains that compare symbols that would consider those numbers 'close'.

In which case a $810 error in a $13k account is a big friggen error, and would violate the standards of the chip he's working on. Now, I don't know HOW he's making sure high order bits are done more accurately than the low order ones, but that's what the article mentions him doing.

Use in MP3 Players

[AmigaHeretic]

So what you're saying is that it might make all my MP3s sound like they are AutoTuned? But the battery will last 30 times longer?

I guess the question is can Cher sue over this technology?

Re:Use in MP3 Players

[phoenix321]

If you bought a popular artist recently, your music is autotuned already.

Anyway, this means that less than 0.1 percent of your decoded audio samples will be less 0.1 percent off. This is probably very acceptable outside concert halls and living rooms if it delivers large bonuses in battery saving or calculation speed.

For example, we could use a much beefier compression algorithm than MP3 or current algorithms even longer on even smaller devices.

wll,

[greenguy]

i scrfcd accrc 4 spd a lng tm ago

Re:wll,

[hackstraw]

This whole thing is old and silly.

Seymour Cray is known for saying "Do you want fast or accurate?" because back then there was no IEEE 754 spec (which is not infinitely precise) for floating point numbers at the time and machines were pretty primitive then and his machine did Newtonian approximations of many numeric calculations that were accurate to a point, just like John Carmack did (in software) with Doom's inverse square root.

The moral of the story is that in 2009 and beyond its probably best to have hardware continue to be accurate. This is why we have digital 1s and 0s instead of some other base of computation.

Now, in software, feel free to make things as sloppy as you want. If your bank (not mine) wants to round 13,000.83 to some other value, then by all means go for it. But I think that most of us are OK with accurate hardware.

Re:wll,

[vux984]

i scrfcd accrc 4 spd a lng tm ago

and it was going so well too... until you got thirsty and told your friend ..

"hy! I wnt sm ck!"

Top Ten Slogans

[AmigaHeretic]

TOP TEN SLOGANS FOR THIS NEW PROCESSOR:

9.9999973251 - It's a FLAW, Dammit, not a Bug

8.9999163362 - It's the new math

7.9999414610 - Nearly 300 Correct Opcodes

6.9999831538 - "You Don't Need to Know What's Inside" (tm)

5.9999835137 - Redefining the PC -- and Mathematics As Well

4.9999999021 - We Fixed It, Really

3.9998245917 - Division Considered Harmful

2.9991523619 - Why Do You Think They Call It *Floating* Point?

1.9999103517 - We're Looking for a Few Good Flaws

0.9999999998 - "The Errata Inside" (tm)

Re:Top Ten Slogans

[gbjbaanb]

TOP TEN SLOGANS:

runs Excel just as well as always :-)

It seems like when you need a precise calculation

[rolfwind]

like financial things, you compare the end product with the end product of the same calculation run either through the chip again or another chip (or increasingly likely another core).

Still would be faster too.

DSP's?

[Zantetsuken]

Isn't that the point of using a DSP? So you can use a slower CPU to run the firmware and the DSP do that grunt work of decoding, thus letting you save power with the low voltage CPU?

My question is, if it's just as well to use a DSP, why not just use a damned DSP?

Re:DSP's?

[Firethorn]

I think the point would be using a DSP/math coprocessor that uses 1/30th the power in exchange for a .001% loss in accuracy for non-essential tasks like music decoding.

I mean, combined with the lousy earbuds most people use, who'd notice? Especially if it makes their MP3 player last 3 times as long as ones that use more traditional and technically accurate DSP/decoder?

Re:DSP's?

[Heather D]

Even with good earbuds this would probably not be noticeable. This will have a huge impact upon DSP systems if it pans out. It could have many other applications as well. Robotics, artificial intelligence, fuzzy logic, neural networks, just to name a few.

Not completely correct

[chthon]

If you read the chapter about the history about the IEEE FP standard in Microprocessors : a quantitative approach, then you will see that in the past accuracy was already sacrificed for speed in supercomputers.

gfx

[RiotingPacifist]

can't this be used in gfx cards, i mean with anti-aliasing and high resolutions it doesn't really matter so much if 1/2 a pixel is #ffffff or #f8f4f0 , hell you can probably even get a pixel entirely wrong for one frame and nobody will care (as long as it doesn't happen too often).

Re:gfx

[retroStick]

I agree. In fact, with real-time photorealistic rendering, these slight deviations would probably make frames look more accurate, since real video is full of low-level random noise.
The film-grain shader on Left 4 Dead wouldn't be necessary any more.

Multimedia processor

[Gerald]

If you're about to join the upcoming avalanche of smartass comments, try reading the UDP-Lite RFC first. For some applications (notably real-time voice and video), timeliness and efficiency are more important than accuracy.

If this means my music player or phone get more battery life, I'm all for it.

Primality testing

[2.7182]

Random algorithms are used all the time. In RSA for example, random primes must be generated. This is done with an algorithm that probably gives the right answer, which is good enough. The chance that it would fail is so tiny as to not matter.

Re:Primality testing

[phoenix321]

Even more so: we intentionally gather entropy to improve the pseudo random numbers. With intentionally inaccurate CPU cores, we could scrap all that and gather entropy en-passant AND be much faster anyway.

Re:Primality testing

[Dahamma]

Yeah, but there is a big difference between "random" and "incorrect".

The errors resulting from undesirable interactions between transistors are probably a lot less random than a good pseudorandom number generator for these purposes.

Re:Primality testing

[Hognoxious]

Random algorithms are used all the time.

I'm not even sure such things exist. Even if you meant pseudorandom, that still has zero to do with the point under discussion.

Re:Hmmm

[BadAnalogyGuy]

You get a one-way ticket to pound-me-in-the-ass prison.

Watch out for your cornhole, bud.

Sacrifices are expected

[LiquidCoooled]

I have spent the last 9 months coding up a dynamic scalable UI for the nokia tablets.

I have had to make huge compromises to accuracy to obtain the desired performance.

I had the choice of using the full featured (but slow) widget sets and graphical primatives which existed already, or find a way to make it work as I expected it to.

The results have left people breathless :)

take a look here: http://www.youtube.com/watch?v=iMXp0Dg_UaY

Re:Sacrifices are expected

[ljw1004]

That was a very confusing video. What I learned from it: you haven't done some stuff, Zoom Fish!, widgets, Zoom Fish!, behind schedule, zoom, Fish!, widget framework, Fish!

I guess it's a system that lets you zoom in on fish?

Suitable for streaming media???

[Anonymous Coward]

I'd like to see executives at CBS explain how nipples showed ON TOP of a superbowl performer's outfit.

Talk about a wardrobe malfunction.

I can see the defense now:

Your honor: We ran probabilistic tests with out processors, and while we couldn't really duplicate the problem, we were able to show a penis during one test run. We'd really like to show it to you, but Ms. Jackson has stated that she would quote "Sue us into the ground" unquote.

Nothing new here...

[chill]

Isn't that essentially what JPEG, MPEG and every other lossy codec or transform does?

Re:Nothing new here...

[chill]

There have been dedicated MPEG encoding and decoding chips for many years. DXR3 comes to mind.

I think the only new twist is applying the idea to general calculations as a whole as opposed to a specific function or set of functions in software. An interesting idea. Maybe we'll end up with double-precision, single-precision and ballpark floats.

Games?

[ndogg]

I could definitely foresee this being used in game systems, especially for graphics.

As long as it mostly looks right, that's all that really matters.

Re:Hmmm

[PitViper401]

But what about the conjugal visits?!

My bank yould love this

[Celc]

I'm sure my bank would love to argue they at least got the 13 right as they skim a penny of every transaction. I'm sure this the most awesome thing since sliced bread, but can we please avoid trying too argue this from the point of peoples bank accounts when it introduces random error.

What a waste of grant money...

[gavron]

Processors that provide different output for the same input cannot be used for anything that wants predictable output.

They can not be used for ANY result that is later used by anything else -- after all, data based on bad data yields bad results.

Next thing you know, some offshore manufacturer will use the "imprecise" (cheaper) chips instead of the "accurate" ones, and simple things we depend on everyday will fail in wonky ways.

A bit-flip on a microwave will make a 30-second timer not expire at 0, and keep going at 99:99 and burn the food.

A bit-flip on a home heating circuit will make 70F appear to be a target heat of 6F and never turn on.

A bit-flip on an MP3 player would have it skip from 65 seconds into the song to 134 second into the song.

These are all results if just ONE BIT were to flip JUST ONCE. The processor described would UNPREDICTABLY and RANDOMLY do worse than actually flip one bit.

What's next -- they'll put three processors in each device and when two of them agree they'll go for it? "Voting Processing" is bs.

E

Re:What a waste of grant money...

[cnettel]

Any system which fails permanently due to a single bit error is unstable and not robust (in the numeric sense). If the system is really critical, you should better be ready for bit errors.

This approach is basically similar to what would be required in analog systems. After all, analog engineering was quite possible. The main of the meat in decoding MP3 is not about seeking in the stream, it's a lot of Fourier and postprocessing of the waveform -- loss there can be completely acceptable.

Re:What a waste of grant money...

[Rockoon]

I am reminded of how some circuits such as sorting networks are designed with redundancy such that a certain amount of sub-component error is tolerable. They will still sort their inputs even if multiple sub-components get their output wrong.

It seems to me that we have already been designing things in a probabalistic manner.. all that these new guys are doing is allowing the error tolerance to be much more liberal.

Re:uhhh....

[Dogtanian]

NEWS FLASH: Binary consists of 1 and 0.

NEWS FLASH: People use computers for calculations with more than single-digit binary results.

"probablistic computing" is another way of saying "sloppy engineering".

No- insisting on excessive precision where an "almost certainly right to within +/- x%" solution would be more than good enough and much simpler to obtain is known as overengineering.

I suspect that the financial examples chosen didn't illustrate the point as well as intended (financial companies generally don't like *any* inaccuracy), but that doesn't change the general principle.

Would you prefer a routing algorithm that gobbled up power and took ages to run for a guaranteed shortest route or one that was far more efficient and 99.9% certain to give a route that was within 3% of the shortest possible distance?

The first thing that comes to mind...

[Lordfly]

...is gaming applications.

Programmers spend a lot of time coming up with algorithms that simulate randomness for AI or cloud generation or landscapes or whatever... if the processor was just wonky to begin with it'd make certain things a lot more natural looking.

It's interesting that AI in games is always touted as being "ultra-realistic", but always ends up being insanely easy to trip up. Having something "close enough" would add just enough realism/randomness to situations to perhaps make games and environment more dynamic.

I wouldn't want these things processing my bank balance, though, unless it rounded up.

A Little Bit of History Repeating

[lobiusmoop]

So basically he's advocating fuzzy logic, which was big in AI research in the 80's?

Re:A Little Bit of History Repeating

[osu-neko]

Sorry, I missed the part back in the 80's where using fuzzy logic caused my processor to consume 1/30th the power.

Re:A Little Bit of History Repeating

[DwySteve]

This is not fuzzy logic. In fuzzy logic 'fuzzy' applies to the 'logic' of the decision-making process (ie, not binary TRUE or FALSE, but 'fuzzy' - somewhere in between). This and this are fuzzy logic.

Basically he uses probability, fuzzy logic uses certainty. It's a hard distinction unless you really like math but if you want to argue it's worth arguing.

Well, it's a *little* more important

[roystgnr]

For example, in calculating a bank balance of $13,000.81, deliberately risking getting the "13" incorrect is fraud that risks $13,000 in damages and $1,000,000 in statutory penalties, and risking getting the "81" incorrect is fraud that only risks $0.81 in damages and $1,000,000 in statutory penalties. Surely saving a couple watt-microseconds is worth that!

Or maybe we could...

[PaulBu]

Maybe we could have a selective accuracy, where programmers can set their needs via registers or direct it to different CPU cores ... just keep using (say, in C) short, int, long, long long (no, AV codecs should not require floating point, but is you wish, there are floats, doubles, long doubles, etc.).

Of course proper implementation of some AV decoder on a modern processor will use available SIMD instructions (MMX and friends) where programmer can easily trade off accuracy (in byte-sized chunks) for speed.

Paul B.

for simulation

[kilraid]

For simulation, Monte Carlo and such statistical sampling this would be perfect. There is already random error - sampling error - so adding a lesser source of error - computational error - while reducing the first would make sense if the computations can be sped up.

Obligatory NASA research

[DirePickle]

From NASA:

Computer scientist Arthur Boran was ecstatic. A few minutes earlier, he had programmed a basic mathematical problem into his prototypical Akron I computer. His request was simply, "Give me the sum of every odd number between zero and ten." The computer's quick answer, 157, was unexpected, to say the least. With growing excitement, Boran requested an explanation of the computer's reasoning. The printout read as follows: THE TERM "ODD NUMBER" IS AMBIGUOUS. I THEREFORE CHOOSE TO INTERPRET IT AS MEANING "A NUMBER THAT IS FUNNY LOOKING." USING MY AESTHETIC JUDGEMENT, I PICKED THE NUMBERS 3, 8, AND 147, ADDED THEM UP, AND GOT 157.

A few moments later there was an addendum: I GUESS I MEANT 158.

Followed shortly thereafter by: 147 IS MORE THAN 10, ISN'T IT? SORRY.

Bad example...

[Firethorn]

It looks like you got sucked into the bad example land. Later on in the article it mentions that it's intended for stuff where accuracy isn't paramount, but where it's not really necessary. Multimedia applications over space/bank calculations.

I mean, there's 1.764 Million pixels in my screen that I'm typing my post on at the moment. Does it really introduce much error if I round it to 1.8M? I'm also running at 60Hz. Do you think that I'd really notice if there's a .01% chance that instead of getting white(255) I get white(254)? That'd be an average of 176 pixels a refresh, assuming an all-white screen. Thing is, those pixels wouldn't be the same every time. Then again, logically each pixel would tend towards red/blue/yellow depending on the error. But only slightly. In a HD movie, are you really going to notice?

Sooo...

[thetzar]

He's invented analog?

Fudgy-Dah!

[WebManWalking]

Nihon-go de amari yokunai hanashimasu. However, I believe that the Japanese expression was pronounced closer to "Fudgy-dah!" in ads.

I live in the Washington, DC, area. One of the big perks of living here is the Library of Congress. You have to undergo a security clearance to get permission to be there, but once you get that photo id, hoo boy, there sure is a lot of information there.

I'm a computer programmer (currently working in Web development, as my handle here suggests). Long, long ago, I researched fuzzy logic at the Library of Congress from the original studies that proposed it. (I think that the original papers were from an Air Force study.) It did NOT revolve around lookup tables. It was more fundamental than that.

Fuzzy logic assigns a floating point number to data that represents how confident you are that it's true. In the early days, the number varied between 1.0 (absolute certainty) to 0.0 (not a clue, wild guess), or even -1.0 (absolutely sure that it's not true). The exact range used is unimportant except that it's well-known. Of course, almost all of these numbers are between whatever limiting numbers you set, representing shades of gray. That's where the term fuzzy came from.

We like to believe that knowledge is a deterministic process, but to believe that, we have to ignore our fundamental assumptions, which force us to admit that we don't really know for sure. Fuzzy logic seeks to improve decision-making by acknowledging that fuzziness and quantifying it.

We all know that we have to multiply percentages to derive percentages based on multiple criteria. If roughly 1 in 2 people are male and exactly 1 in 2 have characteristics above the median, we derive that roughly 1 in 4 of all people are males with intelligence above the median for males. But how confident are we in knowing that?

Say, for a given population, the 1-in-2 statistic for males is about 97% likely to be true. The 1-in-2 statistic for being above the median is 100% likely to be true, because that's the definition of median. So when you combine the 2 criteria, the 1-in-4 statistic still has a 97% likelihood of being true. In other words, fuzzy logic is a completely independent, parallel computation based on the confidence factors that travel with the data.

The fact that confidence factors travel with the data is an important part of fuzzy logic. You never throw the confidence factors away and say "That's it. We got the inference we wanted. It's over 95%. That's close enough, so we're going to treat it as true." If you do that, you've gained no wisdom whatsoever from tracking confidence factors. You have to remember that there's still a 5% chance that you're wrong. So all inferences also have their own confidence factors, which are also not thrown away.

To take an Air Force example, in deference to my vague recollection that they sponsored the original study, satellite surveillance reveals that a bunch of bombers are heading north in Russia. Is it just an exercise, or first evidence of an attack? You have to factor in a lot of unknowns. What's their air speed? How likely are they to be carrying a payload at that speed? Even if they appear to be carrying a payload, how likely is it to be a full dress rehearsal, with ballast for realistic plane handling? The list goes on and on. As part of standard readiness, the confidence factors of these questions have been calculated and recalculated on an ongoing basis. NORAD sees the scenario and looks it up in a scenarios book. As a result, they decide not to change the DEFCON, but they read ahead to see what to do if the bombers leave Russian air space. Crossing the border has a different confidence factor that goes into the overall calculations of whether or not it's likely to be just an exercise.

So no, fuzzy logic is not simply using lookup tables. Lookup tables are just a convenient way to organize inferences based on changing conditions in reality.

Returning to Washington, DC, area fo

Analog?

[w0mprat]

Transistors are naively analog. It's ironic that we use them for digital logic locked to a frequency cycle.

Re:Analog?

[Joe Snipe]

Transistors are naively analog

Oh those simple-minded transistors. When will they learn?

Early Pentium 60 fiasco

[Darkk]

You probably remember when some scientists noticed it was generating some math error in their applications so they contacted Intel about it.

Intel's response was, "Well, these are early processors in design and shouldn't affect 99% of the population". Of course the scientists created an awareness of this issue and public generated a stink about it even though 99% of them may never run into the bug that affects their applications.

So now 15+ years later this pops up saying it is OK to have these errors in non-critical applications for sake of speed. People are going to wonder about these chips in their products when something isn't working right and may cry afoul.

Article badly misrepresents the idea

[Jimmy_B]

The author of the linked article has completely misunderstood what this research is about. It is NOT about tolerating errors in the output of computations; that would be completely infeasible. It's about tolerating errors in intermediate values, by using redundancy. For example, three adders made out of unreliable transistors plus a control unit to have them vote, may be smaller and use less power than one adder made out of reliable transistors. However, you can't make everything out of unreliable transistors. In particular, the control unit, and the parts that compare results to each other, have to work reliably and can't be duplicated. That is what is meant by "some information was more valuable than other information", not the low-order bits of a numeric computation.

And this is a major step forward in the research

[3seas]

.... of artificial intelligence.

Re:Oh God, please don't corrupt audio any further.

[Aphoxema]

You say what you say, but for the life of me, I have never felt concerned with the supposed quality of audio. I just can't tell the difference between 128kbps and 256kbps, MP3 from FLAC, 22khz from 44khz.

I also can not tell the difference between HD and upscaled SD when in motion.

It just feels so ridiculous, I swear people are only fooling themselves in this high-def nonsense. I can't be sure of that, maybe there really is something I'm missing I'm unaware of.

Already here

[Builder]

We already have accuracy issues with the processors available today. I've worked with quant teams who will insist on only having machines with Intel processors in their compute farm, because they get a different result from the same code running on AMD machines. As the business has signed off the Intel numbers, Intel it is.

And nonsensical applications again....

[gweihir]

In order to stream auto or videao meaningfully, you need to play/display the contents. This has energy consumption high enough that energy savings in the computations will not matter at all before long. In addition, such a chip will allways be very special purpose and most IT experts will not be able to programm in. I call this a dead end.

Proof at last...

[Roadkills-R-Us]

... that the economy is now based on Monopoly money.

Now when you log on to your online banking account, you'll get a Chance card:

Bank errors are in your favor... at the moment.