# Blue Gene/P Reaches Sixty-Trillionth of Pi Squared

#### timothy posted more than 3 years ago | from the just-warming-it-up dept.

212
Reader Dr.Who notes that an Australian research team using IBM's Blue Gene/P supercomputer has calculated the sixty-trillionth binary digit of Pi-squared, a task which took several months of processing. Snipping from the article, the Dr. writes: * "'A value of Pi to 40 digits would be more than enough to compute the circumference of the Milky Way galaxy to an error less than the size of a proton.' The article goes on to cite use of computationally complex algorithms to detect errors in computer hardware. The article references a blog which has more background. Disclaimers: I attended graduate school at U.C. Berkeley. I am presently employed by a software company that sells an infrastructure product named PI."*

## Thats what she said (-1)

## Anonymous Coward | more than 3 years ago | (#35987618)

Thats what she said

## Numberists! (2)

## 2.7182 (819680) | more than 3 years ago | (#35987818)

## Re:Numberists! (2)

## biryokumaru (822262) | more than 3 years ago | (#35987852)

## Re:Numberists! (1)

## flappinbooger (574405) | more than 3 years ago | (#35987966)

They should calculate pi*e. Knowing that number to such detail would be... delicious.

That's a pretty sweet comment

## Re:Numberists! (0)

## Anonymous Coward | more than 3 years ago | (#35988272)

## Re:Numberists! (1)

## MyLongNickName (822545) | more than 3 years ago | (#35987892)

I wrote a program to find the nth digit of i^2. It is blazing fast too.

## Re:Numberists! (5, Interesting)

## Eudial (590661) | more than 3 years ago | (#35987970)

Especially given that pi is a stupid constant that makes no sense [tauday.com] .

## Tau? (1)

## colinrichardday (768814) | more than 3 years ago | (#35988228)

## Re:Numberists! (0)

## Anonymous Coward | more than 3 years ago | (#35988680)

## Re:Numberists! (1)

## porl (932021) | more than 3 years ago | (#35988766)

thanks, i found that link really interesting :)

i like when something i had thought in the back of my head while doing school work (way back when) turns out to be something other people have pondered over. it is remarkable to see how much more 'pretty' the maths becomes with this simple change of perspective.

## Different outcomes (5, Funny)

## garcia (6573) | more than 3 years ago | (#35987620)

From the blurb:

Oh, I expected the sentence to end with, "...and I still don't know why the fuck anyone cares about a number this long."

I'm going to the bar. Who's with me?

## Re:Different outcomes (0)

## Anonymous Coward | more than 3 years ago | (#35987788)

I'm in, so long as they serve pi...

## the pi is a lie (0)

## Anonymous Coward | more than 3 years ago | (#35987848)

hm'k?

we know the world is flat and all...

don't let them mad scientists get to ya!

cheers.

## Re:Different outcomes (1)

## kenj0418 (230916) | more than 3 years ago | (#35988028)

Well, I'm going to Pi. http://www.restaurantpi.com/ [restaurantpi.com]

## Re:Different outcomes (0)

## Anonymous Coward | more than 3 years ago | (#35988922)

Well for those of us in the Bay Area, come to Pi Bar instead! http://pibarsf.com

## Re:Different outcomes (1)

## chebucto (992517) | more than 3 years ago | (#35988076)

why the fuck anyone cares about a number this long

Seriously, does anyone have an answer for this? Unless they're waiting to see if the digits start repeating themselves, I don't get why anyone would need a value of pi to be so precise.

Personally, I've assumed that the stupidly-precise values of pi were calculated out of pure obsessiveness and, perhaps, a desire for fame (of a kind).

But if they're using months of time on a very expensive, very new, publicly-funded supercomputer to calculate the value, then there's _got_ to be a reason. Right?

## Re:Different outcomes (2)

## chebucto (992517) | more than 3 years ago | (#35988130)

After waiting minutes for an answer, I decided to RTFA and, well, there is a reason (or at least a good excuse)

one application for computing the digits of Pi is to test the integrity of computer hardware and software, which is a focus of Baileyâ(TM)s research at Berkeley Lab. âoeIf two separate computations of digits of Pi, say using different algorithms, are in agreement except perhaps for a few trailing digits at the end, then almost certainly both computers performed trillions of operations flawlessy"

## Re:Different outcomes (1)

## statusbar (314703) | more than 3 years ago | (#35988662)

They are secretly looking for the digits to form an infinite series of encoded bitmaps of a circles, in order to prove that god has a sense of humour.

--jeffk++

## Re:Different outcomes (-1)

## Anonymous Coward | more than 3 years ago | (#35988334)

This is about Australian pride.

And the ultimate education success story for any Australian is to be able to state truthfully that they attend an American university. Australians love America and Americans. They want to be America and Americans. They like to think they actually are America and Americans.

Which is not surprising really, because anything is better than being Australian.

FEEEEEEESH EEEEND CHEEEEEEPS! SCREEEEEECH! TOY MEEE KENGEROO DOYWN, SPOREEEEEET! SCREEEEEEEEEEEEEECH!

## Re:Different outcomes (1)

## porl (932021) | more than 3 years ago | (#35988776)

yeah, pretty sure you are either not from australia or you are just trolling here.

i am from australia. i know no one who 'wants to be american'. american education is a laughing point in australia (not entirely deserved i guess, but mostly focused on the more prevalent influence of religion in 'science' education in some parts of america).

not sure what the screech crap was there, but i'm sure you thought it was hilarious.

apologies to everyone else for feeding the troll.

## Re:Different outcomes (0)

## Anonymous Coward | more than 3 years ago | (#35988508)

I used to know why I should care, but then I found this hand held power drill...

## Phew (0)

## ImABanker (1439821) | more than 3 years ago | (#35987622)

## pi Squared? (1)

## TaoPhoenix (980487) | more than 3 years ago | (#35987640)

What does that number "do"?

Pi is famous, and the more well known number to crunch. Why crunch Pi Squared? Can't you just square Pi?

## Re:pi Squared? (2)

## MoonBuggy (611105) | more than 3 years ago | (#35987654)

Can't you just square Pi?

Well, yes, but doing so to vast precision requires you to to crunch a vast number of digits of pi, so I imagine it's all largely the same in the end.

## Re:pi Squared? (0)

## Anonymous Coward | more than 3 years ago | (#35987782)

Interestingly, this is actually not true! I read the article, googled for the formula, and found that the number is computed by approximating a series which you can see here: http://mathworld.wolfram.com/BBP-TypeFormula.html .

## Re:pi Squared? (1)

## superwiz (655733) | more than 3 years ago | (#35988292)

## Re:pi Squared? (0)

## Anonymous Coward | more than 3 years ago | (#35988924)

Actually it can be done in just above O(n log n) time using FFTs. See a list of algorithms on Wikipedia [wikipedia.org] .

## Re:pi Squared? (0)

## Anonymous Coward | more than 3 years ago | (#35987814)

Maybe it's easier to compute pi squared, then take it's square root? :-)

## Re:pi Squared? (1)

## 2.7182 (819680) | more than 3 years ago | (#35987844)

## Re:pi Squared? (0)

## Anonymous Coward | more than 3 years ago | (#35988462)

That series converges quite slowly; there must be a better one to use (and I'd be interested to learn of one).

## Re:pi Squared? (1)

## MobileTatsu-NJG (946591) | more than 3 years ago | (#35988138)

What does that number "do"?

Well, for one thing, you could use it to defeat computers in the future.

## Re:pi Squared? (1)

## BeanThere (28381) | more than 3 years ago | (#35988160)

Pi is 'wrong' ... http://tauday.com/

## Re:pi Squared? (1)

## greylion3 (555507) | more than 3 years ago | (#35989202)

Do you mean; what's it used for?

Well, for one thing it's part of the formula to calculate the volume of a torus:

V = 2 * Pi^2 * R * r^2

## How many digists of pi do you know? (3, Informative)

## TroyM (956558) | more than 3 years ago | (#35987644)

http://www.toothpastefordinner.com/031208/how-many-digits-of-pi-do-you-know.gif [toothpastefordinner.com]

## Re:How many digists of pi do you know? (3, Interesting)

## MoonBuggy (611105) | more than 3 years ago | (#35987672)

Re:How many digists of pi do you know?

## Re:How many digists of pi do you know? (2)

## jamesh (87723) | more than 3 years ago | (#35988006)

about 5 probably. My daughter can recite 50 or 100 or something like that.

## Re:How many digists of pi do you know? (2)

## arth1 (260657) | more than 3 years ago | (#35989096)

"50 or 100 or something like that"?

That's like saying you have "1 or 2 cars or something like that" -- far too imprecise to be useful. In fact, 0 would satisfy "50 or 100 or something like that".

## Re:How many digists of pi do you know? (4, Informative)

## the_humeister (922869) | more than 3 years ago | (#35988100)

I know all of them. I just don't know which order they go in.

## Re:How many digists of pi do you know? (1)

## rrohbeck (944847) | more than 3 years ago | (#35988300)

OK I'm a dick.

50.

## Re:How many digists of pi do you know? (4, Informative)

## Abstrackt (609015) | more than 3 years ago | (#35988308)

## Re:How many digists of pi do you know? (2)

## arth1 (260657) | more than 3 years ago | (#35989154)

"How I want a drink, alcoholic of course, after the heavy lectures involving quantum mechanics!" There you go, Pi to 14 digits in an easy to remember package. Count the letters in each word to get the right digits.

Easily beaten by this common and far more memorable verse:

How I wish I could enumerate Pi

"Eureka!" cried the great inventor

"Christmas pudding, Christmas pie

is the problem's very center!"

After hearing that one once, I could not help but remember pi to 20 decimals.

If I want to be more precise, arccos(-1) will do.

## YTMND inspired a lot of people to learn (1)

## tepples (727027) | more than 3 years ago | (#35988672)

## Only one binary digit? (1)

## maxwell demon (590494) | more than 3 years ago | (#35987652)

So they just calculated that one binary digit?

Was it a 0 or an 1?

## Re:Only one binary digit? (4, Funny)

## stillnotelf (1476907) | more than 3 years ago | (#35987698)

## Re:Only one binary digit? (2)

## Daniel Dvorkin (106857) | more than 3 years ago | (#35987886)

1, in base pi.

## Re:Only one binary digit? (0)

## Anonymous Coward | more than 3 years ago | (#35988202)

I can instantly compute any binary digit of PI with a .5 certainty

## Pi for spheres? (0)

## Anonymous Coward | more than 3 years ago | (#35987676)

Is there the equivalent to pi in three dimensions? I mean, the ratio of a sphere's surface area to the area of the circular plane bisecting it? Maybe it has no significance.

## Re:Pi for spheres? (0)

## Anonymous Coward | more than 3 years ago | (#35987702)

Is there the equivalent to pi in three dimensions? I mean, the ratio of a sphere's surface area to the area of the circular plane bisecting it? Maybe it has no significance.

That number is 4

## Re:Pi for spheres? (1)

## maxwell demon (590494) | more than 3 years ago | (#35987770)

Is there the equivalent to pi in three dimensions? I mean, the ratio of a sphere's surface area to the area of the circular plane bisecting it? Maybe it has no significance.

That number is 4

Well, three dimensions are just more rational. :-)

## Re:Pi for spheres? (1)

## cwebster (100824) | more than 3 years ago | (#35988136)

solid angle

## Not a disclaimer ... (2, Informative)

## Anonymous Coward | more than 3 years ago | (#35987690)

"Disclaimers: I attended graduate school at U.C. Berkeley. I am presently employed by a software company that sells an infrastructure product named PI.""

That's *not* a DISCLAIMER. That's a DISCLOSURE.

## Re:Not a disclaimer ... (1)

## Anonymous Coward | more than 3 years ago | (#35987900)

Its not a disclosure, it is an advertisement.

## Re:Not a disclaimer ... (1)

## MobileTatsu-NJG (946591) | more than 3 years ago | (#35988146)

Doesn't that bring us back to the word 'disclaimer'?

## Re:Not a disclaimer ... (0)

## Anonymous Coward | more than 3 years ago | (#35988630)

And it's a pointless disclosure at that

If he had been involved in the validation it would have been a different story but as it stands WHO CARES!

## Re:Not a disclaimer ... (1)

## tepples (727027) | more than 3 years ago | (#35988706)

## I asked for the square root of PI! (0)

## Anonymous Coward | more than 3 years ago | (#35987696)

Not PI squared, who would ever want more than fifteen digits of that? But the square root of PI... that is where we require 18 trillion decimal digits.

## And yet (1)

## proverbialcow (177020) | more than 3 years ago | (#35987704)

## Re:And yet (1)

## proverbialcow (177020) | more than 3 years ago | (#35987730)

## Balls (1)

## proverbialcow (177020) | more than 3 years ago | (#35987758)

1.67E-13 is FAR larger than 2^-6E13. Stupid math.

## Re:And yet (0)

## Anonymous Coward | more than 3 years ago | (#35987894)

Actually, since it's a bit, lets just say it's 0.5. In which case the error of margin is 0.5 as well.

## Re:And yet (1)

## SilverHatHacker (1381259) | more than 3 years ago | (#35987942)

## Round with pumpkin please. (1)

## Qatz (1209584) | more than 3 years ago | (#35987720)

## Didn't get into Stanford? (0)

## Anonymous Coward | more than 3 years ago | (#35987828)

Disclaimer: I go to Berkeley so I am better than you.

## Pi not useful at galactic scale to high accuracy (0)

## DCFusor (1763438) | more than 3 years ago | (#35987860)

## Re:Pi not useful at galactic scale to high accurac (0)

## Anonymous Coward | more than 3 years ago | (#35987890)

Wow. You figured that out yourself. You are a freaking genius of the highest order. Please carry my babies do they might be as smart as you someday.

No shit, sherlock. The whole point is to give an idea of the meaning of 60 trillion digits. If 40 is more than enough for any imaginable purpose, then 60 trillion is completely ridiculous. No one was suggesting you'd use pi to measure the diameter of a galaxy.

if you were really smart, which you aren't, you would realize that

1) The galaxy is not circular

2) The meaning of "galaxy" is quite ambiguous and it certainly does have a clearly defined border... much like our atmosphere

3) That your mom should have aborted you.

## Re:Pi not useful at galactic scale to high accurac (2)

## martin-boundary (547041) | more than 3 years ago | (#35988074)

## Error in, error out (1, Interesting)

## macslas'hole (1173441) | more than 3 years ago | (#35987884)

... enough to compute the circumference of the Milky Way galaxy to an error less than the size of a proton

Why bother carrying out the computation to such precision when the error in your measurement of the radius (or diameter) would be so much bigger.

## Re:Error in, error out (1)

## PatrickThomson (712694) | more than 3 years ago | (#35988004)

It sounds like you think that's a statement about the pi they've calculated here, where the words immediately preceeding your quote, found at the top of this page, are "pi to 40 digits". Any of us could comfortably calculate that on paper in a day, or half an hour with a 10-digit solar powered calculator. I fear you may be guilty of slashdot-itis - an impulse to try and prove yourself smart by demolishing a strawman built from the headline, or the summary if we're lucky. Sometimes, the fail is too epic not to rebuke.

## Re:Error in, error out (2)

## martas (1439879) | more than 3 years ago | (#35988184)

## Pi r round (1)

## jd (1658) | more than 3 years ago | (#35987888)

Not square.

## Re:Pi r round (0)

## Anonymous Coward | more than 3 years ago | (#35987946)

Tell that to Gina.

http://thesquarepie.com

## Re:Pi r round (1)

## flappinbooger (574405) | more than 3 years ago | (#35987978)

Not square.

Besides, a square pi is more of a cobbler, don't you think?

## Re:Pi r round (1)

## rossdee (243626) | more than 3 years ago | (#35988204)

Back in the land where I was born we had 'meat pies'. They weren't square exactly, more like rectangular with rounded corners.

(No Apple Computer (TM) had nothing to do with it.)

I only ever bothered memorizing 10 digits of Pi since that was the number of digits calculators had (back in '74 - it was an HP35

## Re:Pi r round (1)

## jd (1658) | more than 3 years ago | (#35988822)

In Ye Olde Country, the strangest meat pie was the crescent-moon-shaped Cornish pastie.

## Exact value of PI-squared was determined long ago (0)

## Anonymous Coward | more than 3 years ago | (#35987924)

By the Indiana legislature; it's 9.0.

## "Outstanding" (0)

## Anonymous Coward | more than 3 years ago | (#35987928)

## stupid... (0)

## Anonymous Coward | more than 3 years ago | (#35987934)

There is no point to this. Pi is an irrational number you can't digitize. Just continues to promote the ignorance of the nature of Pi.

## Re:stupid... (1)

## MichaelSmith (789609) | more than 3 years ago | (#35987950)

But there might be a circle in there.

## BG/P (1)

## 1729 (581437) | more than 3 years ago | (#35987944)

Wow, a BlueGene/P is being used to run something other than Linpack. That's gotta be a first.

Disclaimer: I didn't attend graduate school at U.C. Berkeley, nor am I presently employed by a software company that sells an infrastructure product named PI. I have, however, wasted way too much time trying to get codes to build and run (slowly!) on BG/* platforms.

## Easy to calculate (2)

## Lulu of the Lotus-Ea (3441) | more than 3 years ago | (#35987992)

It's plain easy to calculate the sixty-trillionth digit of Pi... as long as you don't care about the digits that come before it: http://www.sciencenews.org/sn_arc98/2_28_98/mathland.htm [sciencenews.org] .

## Re:Easy to calculate (1)

## Aldenissin (976329) | more than 3 years ago | (#35988098)

20 computers a month for the trillionth, much less all 60... trillion. A month with 20 computers for one digit still doesn't seem that straight forward.

## Re:Easy to calculate (1)

## godrik (1287354) | more than 3 years ago | (#35988126)

GP point is that computing a particular digit of pi is easy, you can even compute it manually. So in particular the 60 trilionth digit is easy to know. Knowing the first 60 trilionth digit is a much harder task.

## Re:Easy to calculate (0)

## Anonymous Coward | more than 3 years ago | (#35988762)

untrue, plouffes method lets you trade binary splitting and fft for 8 bit word multiplies but you still have to do an amount of work proportional to 60 trillion, its just easier to implement at massive scale.

## I know the last digit of pi... (1)

## synaptik (125) | more than 3 years ago | (#35988020)

I know the last digt of pi! It's zero... in base pi.

## Pizza pi (0)

## Anonymous Coward | more than 3 years ago | (#35988078)

http://www.bash.org/?696997

what is the volume of a pizza of radius z and thickness a ?

answer: pi z z a

## Base 10 - Bah! (1)

## S-100 (1295224) | more than 3 years ago | (#35988124)

## Re:Base 10 - Bah! (0)

## Anonymous Coward | more than 3 years ago | (#35988210)

Oops. I guess you mean pi = 10 and pi squared = 100. Still computed in a nanosecond (sort of), but now correct!

## Re:Base 10 - Bah! (1)

## Mt._Honkey (514673) | more than 3 years ago | (#35988248)

You humans and your base-10 arithmetic. I use base-pi arithmetic. So pi = 1, and pi squared = 1. Computed in a nanosecond. Of course, it makes other computations slightly more complex. For example, I have about 3.183095825842514 fingers, more or less...

You just took 10 and divided it by pi and wrote that down, all in base 10. Also, pi in base pi would be 10, not 1 (like 2 is 10 in binary), and pi^2 is 100.

I'm not certain how other numbers in a non-integer base would be written down, but I think 10 in base pi would be 100.010221222... (pi^2 + pi^-2 + 2*pi^-4 + 2*pi^-5...) There may be multiple representations of the same number. For example, I think 10 could also be 30.121...

## What a waste of time! (1)

## SpeZek (970136) | more than 3 years ago | (#35988206)

## Re:What a waste of time! (2)

## aquila.solo (1231830) | more than 3 years ago | (#35988480)

## Well??!? Is it 1 or 0? (1)

## pem (1013437) | more than 3 years ago | (#35988214)

Of course, this being slashdot, I didn't RTFA.

## Universe (1)

## pgn674 (995941) | more than 3 years ago | (#35988220)

Question: Knowing the diameter of the observable universe, how many digits of Pi are needed to calculate the circumference of the observable universe, accurate to within 1 plank length?

Answer: 62 digits. Here they are: 3.14159265358979323846264338327950288419716939937510582097494459

Calculated this one myself.

## Re:Universe (0)

## Anonymous Coward | more than 3 years ago | (#35988806)

planck. planck!

## A time to crack wise... (2)

## Torodung (31985) | more than 3 years ago | (#35988230)

I think it would be tremendously funny to find out, at some suitably ridiculous decimal place, that all subsequent places are zero repeating. It would utterly break some people's heads to find out that the number is only "very, very particular," rather than "irrational."

It is the one hope that holds my interest when I read about crunching these numbers.

## Re:A time to crack wise... (3, Informative)

## Anonymous Coward | more than 3 years ago | (#35988382)

I'm sorry to destroy your one hope. [wikipedia.org]

## Re:A time to crack wise... (0)

## Anonymous Coward | more than 3 years ago | (#35988458)

Hopefully this doesn't break your head too much: http://en.wikipedia.org/wiki/Proof_that_%CF%80_is_irrational [wikipedia.org]

## Feynman point (1)

## tepples (727027) | more than 3 years ago | (#35988734)

There is a sequence of several 9's [wikipedia.org] fairly early in the decimal expansion of pi though. People have joked about memorizing pi out to 770 digits so they can say "...999999 and so on."

But seriously, the irrationality of arctan(1) (which equals tau/8 or pi/4) has been proven [wikipedia.org] .

## Nerds (1)

## DSS11Q13 (1853164) | more than 3 years ago | (#35988474)

Pi = 3

## This isn't much different than SETI (0)

## Anonymous Coward | more than 3 years ago | (#35988552)

If anyone remembers Sagan's novel Contact (quote from wikipedia):

## What's the purpose of doing the calculation? (0)

## Anonymous Coward | more than 3 years ago | (#35988782)

I mean are they expecting some kind of repeating value or pattern? Wouldn't the computational time be better spent determining when the Leafs will win a Stanley Cup?