Many digits of pi again
01-27-2014, 06:44 AM
Post: #1
 Benoit Maag Junior Member Posts: 42 Joined: Jan 2014
Many digits of pi again
This is in reference to the article by Katie listing several programs for various machines to calculate many digits of pi in record time, posted Oct 17, 2008

Some programs manage 6 digits per memory, some 7 or 8. I suspect the choice is based on a combination of internal precision of calculation and the number of terms calculated. Is there a thread describing how to select the number of digits per memory? Or can someone clarify that? (Katie?)

Thank you - sorry if this is a repeat

Benoit
01-27-2014, 07:52 PM (This post was last modified: 09-29-2014 02:29 PM by Katie Wasserman.)
Post: #2
 Katie Wasserman Super Moderator Posts: 625 Joined: Dec 2013
RE: Many digits of pi again
(01-27-2014 06:44 AM)Benoit Maag Wrote:  Some programs manage 6 digits per memory, some 7 or 8. I suspect the choice is based on a combination of internal precision of calculation and the number of terms calculated. Is there a thread describing how to select the number of digits per memory? Or can someone clarify that? (Katie?)

Yes, you've got that exactly right.

The argument gos something like this:

I have a 10-digit calculator so I can fit 8 digits into each memory register allowing for multiplication/division of up to 2 digits. So now I can calculate up to 1000 digits. But at XXX digits I need 3 digits in my multiplication/division so I can only use 7 digits per register.

You can write a simple formula for this but there are idiosyncrasies of each calculator that need to be taken into consideration and certain programing tricks allow for more (or less) precision, etc.. It's not easy to figure out the maximum number of digits unless you error on the side of caution or do it experimentally.

The 16C is a fun calculator to play this game on since it gives you such nice control over the word size.

-katie

03-22-2014, 01:34 AM
Post: #3
 Frozen North Junior Member Posts: 18 Joined: Mar 2014
Verification using Linux
There is the program pi available on Linux systems which calculates π to a specified number of decimal digits.

On a Linux machine connected to the Internet, at a terminal command line enter:
Code:
sudo apt-get install pi
The man page for pi gives the usage details.

Example:
Code:
\$ pi 64 3.141592653589793238462643383279502884197169399375105820974944592

Before installing the program, you might want to update your system.
Code:
sudo apt-get update sudo apt-get upgrade
The above could take a while.
03-23-2014, 12:11 AM
Post: #4
 Geir Isene Senior Member Posts: 567 Joined: Dec 2013
RE: Many digits of pi again
Wow - way cool. Didn't know about the "pi" program.

Brings memories. Me and a friend started a Society for Memorizing and Understanding Universal Constants in high school. The requirement for membership was to recite pi to 52 decimals and e to 34 decimals. And the chairman was the one who at a given time could recite the most decimals of pi. So, when my friend had social sciences, he was sure to be the chair after the class. Whenever I had French, I got out on top. We got to around 350 decimals before we found other fun stuff to do. We never got to be more than three members, though :-)
03-23-2014, 12:20 AM
Post: #5
 davetheguru Junior Member Posts: 28 Joined: Jan 2014
RE: Many digits of pi again
isn't it pointless to calculate it when it exists other places out more places than you can hope for on a calculator?
http://www.piday.org/million/

On a clear disk, you can seek forever.
03-23-2014, 12:23 AM
Post: #6
 Massimo Gnerucci Senior Member Posts: 1,462 Joined: Dec 2013
RE: Many digits of pi again
(03-23-2014 12:20 AM)davetheguru Wrote:  isn't it pointless to calculate it when it exists other places out more places than you can hope for on a calculator?
http://www.piday.org/million/

Oh well... almost everything can be made faster and better than on a calculator.
Isn't it?

Greetings,
Massimo

-+×÷ ↔ left is right and right is wrong
03-23-2014, 01:42 PM
Post: #7
 Dieter Senior Member Posts: 1,888 Joined: Dec 2013
RE: Many digits of pi again
(03-23-2014 12:11 AM)Geir Isene Wrote:  Wow - way cool. Didn't know about the "pi" program.

With internet access, the only program required to get thousands of digits of pi is a web browser. ;-)

(03-23-2014 12:11 AM)Geir Isene Wrote:  The requirement for membership was to recite pi to 52 decimals and e to 34 decimals.

52 and 34? Why that?

(03-23-2014 12:11 AM)Geir Isene Wrote:  We got to around 350 decimals before we found other fun stuff to do.

Ah, those were the days, when memorizing pi was "fun stuff". :-))

(03-23-2014 12:11 AM)Geir Isene Wrote:  We never got to be more than three members, though :-)

Fun for a selected audience, that is. ;-)

Dieter
03-23-2014, 01:53 PM
Post: #8
 Geir Isene Senior Member Posts: 567 Joined: Dec 2013
RE: Many digits of pi again
(03-23-2014 01:42 PM)Dieter Wrote:
(03-23-2014 12:11 AM)Geir Isene Wrote:  Wow - way cool. Didn't know about the "pi" program.

With internet access, the only program required to get thousands of digits of pi is a web browser. ;-)

But the pi program is a) working offline, b) faster, and c) way much cooler.

(03-23-2014 01:42 PM)Dieter Wrote:
(03-23-2014 12:11 AM)Geir Isene Wrote:  The requirement for membership was to recite pi to 52 decimals and e to 34 decimals.

52 and 34? Why that?

Due to the obvious significant of those numbers ;-)
(actually, I don't remember why)
02-12-2015, 07:06 PM
Post: #9
 Den Belillo (Martinez Ca.) (not so much Super as average) Moderator Posts: 478 Joined: Dec 2013
RE: Many digits of pi again
the final word on this subject: http://www.smbc-comics.com/index.php?id=3639
02-12-2015, 10:59 PM
Post: #10
 rprosperi Senior Member Posts: 2,557 Joined: Dec 2013
RE: Many digits of pi again
(02-12-2015 07:06 PM)Den Belillo (Martinez Ca.) Wrote:  the final word on this subject: http://www.smbc-comics.com/index.php?id=3639

Thanks Den! I know just the people to send this too... we too were a group of guys that tried to out-memorize each other with digits of PI. One of them brought in an article once that showed it could be calculated as an infinite series, and we just pooh-poohed him. He will really enjoy this today.

--Bob Prosperi
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