## 5 Trillion Digits of Pi — a New World Record 299

Posted
by
timothy

from the obsessions-unleashed dept.

from the obsessions-unleashed dept.

KPexEA writes

*"Alexander J. Yee & Shigeru Kondo claim to have calculated the number pi to 5 trillion places, on a single desktop and in record time. The main computation took 90 days on Shigeru Kondo's desktop. Verification was done using two separate computers. The program that was used for the main computation is y-cruncher v0.5.4.9138 Alpha."*Looks like the chart of computer-era approximations of Pi here might need an update.
## Update... (Score:1, Informative)

Looks like the chart of computer-era approximations of Pi here might need an update.

This chart is very outdated anyway.

It doesn't even list Daisuke Takahashi (2009, 2.576.980.370.000 digits), and Fabrice Bellard (2010, 2.699.999.990.000 digits) [slashdot.org]

## Re:Update... (Score:4, Informative)

Wikipedia has a much better page available.

http://en.wikipedia.org/wiki/Chronology_of_computation_of_%CF%80 [wikipedia.org]

## Re:Trillion? (Score:4, Informative)

This page has more details [numberworld.org], what I find interesting is that he needed 96.0 GB of ram to do the number crunching.

## Re:KGB it! (Score:4, Informative)

The BBP formulas handle this. A quick Google for Bailey-Borwein-Plouffe should give you all the citations you ever need.

A working example of the BBP formula can be found in Javascript on this webpage. http://www.csc.liv.ac.uk/~acollins/pi

Warning: it WILL hang some web browsers as the author does not use web worker API.

## Re:So is there a message (from God?) (Score:5, Informative)

The aliens are vague about the location of the message (it might be in pi) so the Foster character runs software to search for it. Right at the end of the book her program finds a pattern (A circle drawn in 1s and 0s in an 11 by 11 matrix). This pulls together the thread in the book about belief in god vs religion. It turns out that somebody made the universe after all, and the Christians had been (sort of) right all along, though the scientists were right to demand evidence.

I love both the book and film. Thats unusual for me. The Postman was a fantastic book. Don't get me started on the movie.

I often put the DVD of Contact on just to watch the sequence where Fosters character first hears the signal and her crew reconfigure the telescope to analyse it. Its a classic tech scene.

"Once upon a time I was a hell of an engineer"## Re:Trillion? (Score:3, Informative)

last time i checked, trillion was not a proper SI prefix.

what you probably mean is "tera-", but in my native language a trillion is 10^18, which would be the "exa-" SI prefix.

check this: http://en.wikipedia.org/wiki/Long_and_short_scales

## Re:Are they exact? (Score:5, Informative)

If you want to prove that all the digits are correct, you only have to check a few things:

1. There is a sound mathematical proof that the algorithm used in fact does generate the digits of pi, and

2. The algorithm was coded correctly. This should be even easier to check, though likely more tedious.

Now, what it's good for is a little harder. There is no physical application for such a highly accurate value of pi (39 digits should be sufficient to calculate the circumference of the known universe given its radius to within the diameter of a hydrogen atom). However, large numbers of digits of pi are useful as arguments in number theory, statistics, and information theory. For instance, there is no real proof that pi is a normal number [wikipedia.org], but as more digits of pi are found and the statistical properties of the digits are analyzed and shown to be consistent with the definition of normal numbers, that makes the conjecture that pi is actually normal a little closer to being true (see experimental mathematics [wikipedia.org]).

## Corrections follow... (Score:5, Informative)

Yes, we do.

Mathematicalalgorithms, i.e., equations on paper.Absolutely not. The algorithms have to run on practical, exists-on-the-Earth-today computers. Try to multiply two, million-digit numbers together on your laptop and you'll see what I mean. These achievements are

all aboutcomputational optimizations. RTFA -- especially the sections entitled "Arithmetic Algorithms" and "Maximizing Scalability." Even the algorithm used for multiplication changes (dynamically!) during the program's execution, based on the size of the operands.Not even close. The computations are so long, and so intense, that errors caused by hardware imperfections can be expected, so error detection and correction algorithms have to be added. If "I left my pi calculating program running longer than the last guy" it would not produce the correct result -- even if the data structures and algorithms it used were up to the task.

In a word, yes. Could you do it? It's a very, very difficult technical feat, one that required hardware powers and software abilities far beyond those of mortal men. Besides, you're worried about newsworthiness when the two previous /. articles are on wall-climbing robots and the popularity of video game arcades in New York?

This isn't about needing pi to 5 trillion digits. This is about learning how to do large computations faster. Like, improving the state of the art.

## Re:So is there a message (from God?) (Score:5, Informative)

"Taken aback "Really, why?"

-"We have proof, when PI is expended out to (some number), there is a message"..."

Duh.

http://everything2.com/title/Converting+Pi+to+binary%253A+Don%2527t+do+it%2521 [everything2.com]

## Re:They're doing it wrong (Score:3, Informative)

Pi should be calculated in base 3.141593...

You're out on the 6th decimal digit (unless you're going to stop there). Pi is greater than 3.1415926 and less than 3.1415927.

Have I been trolled?

## Re:KGB it! (Score:4, Informative)

Actually the last digit of PI is 1 in binary.

As 0.1b is the same as 0.10b

## pi is Wrong (Score:2, Informative)

## That is one expensive single system (Score:2, Informative)

Prices from Newegg and CDW (Newegg doesn't carry the memory)

CPU(s) $3,446.30

Memory $6,708.00

MB $359.00

Disks $3,599.84

Disk controllers $1,058.00

OS $659.00

Case/Misc $500.00

Total $16,330.14