Pi on the Web

by Shelley Walsh ©2000

The number pi has played a big role throughout history in mathematics. I have also found that it plays a major role on the internet, so I wrote an internet pi tour to help mathematics students and others find the best material about it for whatever their interests are.

Tour

Ask Dr. Math
http://forum.swarthmore.edu/dr.math/faq/faq.pi.html
This is the best place to start to find out about this much talked about number. Dr. Math is a feature of the Math Forum, an online math education community center. This is a good place to clear up many of the common student confusions about pi and irrational numbers in general. Most of the commonly asked questions are answered here in the Pi FAQ and if you don't see your question you can submit it and one of their knowledgeable volunteers will answer it for you. There are also a number of good links here for further exploration. Pilinks is a particularly good one.
Friends of Pi Club
http://www.ast.univie.ac.at/~wasi/PI/
This is a slightly lighter look at pi. If you really get interested in pi you can join this club. but you have to meet the entrance requirement, which is to have the first 100 digits of pi memorized. But you don't have to be a member to use the page. On this page you can find out about probably the first recitation of digits of pi in free-fall, but it is possible to explore more serious interests as well. You can explore some of the nice pi dedicated pages that some of the members have created or find out about more sources for pi on the internet by visiting The Uselessness of pi and its irrational friends.
Pi Mathematics
http://www.ncsa.uiuc.edu/Edu/RSE/RSEorange/buttons.html
Next on the tour is an example of the internet being used to study pi in classes. The  Pi Mathematics Project is a collaborative interdisciplinary project for fifth through eighth graders.
Pi through the ages
http://www-groups.dcs.st-and.ac.uk:80/~history/HistTopics/Pi_through_the_ages.html
The is the best site I have found to start an exploration about the history of pi. It is part of the MacTutor pages on the history of mathematics. If you click on 'Rhind Papyrus' you can see a picture of this ancient Egyptian document. One very nice feature of the Mac Tutor pages is that they have a large collection of biographies of mathematicians and the names of the mathematicians mentioned in the articles are linked to the biographies. Especially to be recommended is the Archimedes biography with its many links to other material on the web.
Pythagorean Triples
http://www.access.ch/circle/text1.html
This is perhaps the most fascinating pi page that I found. It shows a method similar to that of archimedes for finding approximations of pi that can be explained without too much trouble to not very advanced math students. It shows a method for getting as close an approximation for pi as you like without using anything more complicated than the Pythagorean Theorem.
Archimedes' Approximation of Pi
http://itech.fgcu.edu/faculty/clindsey/mhf4404/archimedes/archimedes.html
Here is another presentation of Archimedes' work on pi. This one appears to be somewhat closer to Archimedes' original than the one in MacTutor. It is an annotated version of a translation of the original, so it is done without the use of trigonometry.
The Irrationality of Pi
http://www.mcs.csuhayward.edu/~malek/Mathlinks/Pi.html
How do we know that pi is irrational? It was proven by Lambert in 1761. Here is a proof, but be warned, it takes more than elementary geometry to understand it.
The Pi Pages
http://www.cecm.sfu.ca/pi/
This page deals mainly with the computation of pi. How are computers used to find large numbers of digits of pi? This is the place to find out. Find out about a formula discovered by David Bailey of NASA/Ames and Peter Borwein and Simon Plouffe of the Centre for Experimental and Computational Mathematics at Simon Fraser University for computing the nth digit of pi without the preceding ones. You can also hear the digits of pi spoken in your choice of a large number of languages.
Buffon's Needle
http://www.mste.uiuc.edu/reese/buffon/buffon.html
The next two stops are pages about experimental methods for finding pi and connections between pi and probability. This one involves calculating pi by tossing a needle.
Relative Primes
http://www.pvv.unit.no/~eddie/pi/
In this stop you can participate in a method for computing pi that has to do with the probability of two numbers randomly chosen being relative prime.
Stonehenge
http://witcombe.sbc.edu/EMIntro.html
Is there a reason that a group of the stones in Stonehenge loks like the pi symbol? Some people think there is some mystical connection between this and the fact that the stones are arranged in a circle. From this site there are links both to a page about pi and to one about Stonehenge, so you can make up your mind yourself about the matter. Keep in mind, though, that the first use of this symbol for pi was in 1706 by William Jones. Ah, but his was Welsh, perhaps that has something to do with it.
Pi The Movie
http://www.pithemovie.com/
Now for some entertainment, at this stop we go to the movies.
Contact, the book
http://www.amazon.com/exec/obidos/ASIN/0671004107/o/qid=921074549/sr=2-1/002-5191260-5336253
Pi also plays a significant role in Carl Sagan's book Contact, so if you're interested in pi, I highly recommend this book. The movie is good too, but it leaves out the part about pi, so for that you will have to read the book.
The Joy of Pi
http://www.joyofpi.com/
At this stop you can learn about another book, one entirely about pi. There is also a lot you can find out about pi just from these pages, and there is an excellent page of links. Some links I especially recommend checking out are the Extraordinary Pi Page, Elias' Pi Page, and Mike Keith's Poe E: Near a Raven.
Dale's Pi Page
http://www.geocities.com/SiliconValley/Pines/5945/
At this stop you get to see a page about pi written by 14 year old Dale Winham in Sioux Falls,  South Dakota. It is one of the nicest pi pages I have seen and has a great variety of fun material. His 'Fun and interesting facts about Pi' page is particularly to be recommended and his history page is also quite good.
The Pi Trivia Game
http://www.cid.com/~eveander/trivia/

And now it's time for a quiz.

Additional Links

General

The Ridiculously Enhanced Pi Page
This is the San Francisco Exploratorium's pi page. The main feature here is the celebration of Pi Day, Mar. 14 at 1:59:26. This is also Einstein's birthday, which is celebrated with it.
Daras Pi Page
This is a very beautiful page, but it loads slowly.
Extraordinary Pi
This page has a lot of fun facts about pi and also what claims to be the largest collections of pi links, but it isn't.
Elias' Pi Page
The really interesting thing about this page is that he has converted the binary expansion of pi both to digitized sound and to a digitized picture, so you get to hear and see pi. He has then done some filtering effects on the pictures.
A Slice of Pi Home Page
Paul's Page of Pi
A well designed informative site.
verbose.net
This is an interesting page, but it is very slow loading.

Mathematics and Computing

LucyTuning - LucyScaleDevelopments - Notes on Pi and Phi
This page has information both on pi and on phi, the ratio of the sides of the golden rectangle.
Is Pi normal?
Inverse Symbolic Calculator
One Billion Digits of Pi
Fun with PI
This contains the main formulas for computing pi.
Stu's Personal pi page
Timings for PC programs for computing pi. Also some links to sites having to do with computation of pi.
Archimedes' Constant
This has another presentation of Archimedes Method along with a number of other things and lots of links and references.
The Miraculous Bailey-Borwein-Plouffe Pi Algorithm
How to compute digits of pi ?
This is from the Frequently Asked Questions in Mathematics pages.
Pi and the Fibonacci Numbers
There is a good presentation of the arctan methods for computing pi here.

Programs

Armpi 3 - program to calculate pi for the ARM
apfloat
Apfloat is a high performance arbitrary precision package. That means you can do calculations involving millions of digits with it. It sounds like a good program to download if you want to play around with computing pi, but I haven't checked it out.
Computing Pi

History

History of Mathematics - Pi: It Will Blow Your Mind
A survey on the history of pi with an emphasis on computation formulas.
Pi History
This is Dale's History of Pi page. It is quite good.
Yet another story of pi
A short survey of the history of pi by Lazarus Mudehwe.
Pi in the sky
Some of the records in the calculation of pi over the centuries.
Table of computation of Pi
This a timeline for when various numbers of digits of pi were computed.
PI in the Bible
#Y26. PI in the Bible
Archimedes and the Computation of Pi
This has some background information about Archimedes and a simulation of Archimedes method for finding pi. There are also some pi and general history of mathematics links.
Archimedes and the Square Root of 3
This is a very interesting page about a conjecture about how Archimedes estimated the square root of 3, an estimation that was necessary for his estimation of pi.
Pi
Aryabhata's calculation of pi is given in stanza 10 of his Aryabhatiya. (India 5th c.)
Indiana bill sets the value of pi to 3
The text of the 1897 Indiana State Legislature bill to set the value of pi to 3.

Biography

Archimedes page
Aryabhata
Al'Khwarizmi
MOHAMMAD BIN MUSA AL-KHAWARIZMI
Van_Ceulen
Van Ceulen's Home Page
Wallis
Wallis John
Gregory
Gregory [Gregorie], James
Lambert
Lindemann
Jones
Jones, William
Ramanujan

Class Projects

The Pi Page
This is a page for a school project about pi. There are some fun things in it including a joke about cooking a pi complete with a recipe.
NTTI: How High is Pi?
WNET National Teacher's Training Institute site. Suggested activities to accompany a video about pi. Grades 9-12
Pusic's Pi Links
This is a site for a project about finding out about pi through the internet that was done in a class at Simon Frasier University in British Columbia.
Math Forum: Pi Necklace
This is a about a suggestion for a Pi Day project from 7th grade teacher Diana Funke. The idea is to make a necklace with the colors of the beads representing the different digits.

Art and Entertainment

A Pi Poem by Eve
A poem about pi by Eve Anderson, the writer of the trivia quiz.
RedFrog - Poems from the planet Earth - Wislawa Szymborska
Another poem about pi.
Poe, E.: Near a Raven
Constrained poetry. Mike Keith has constructed a revised version of Poe's The Raven so that the numbers of letters in successive words spell out the digits of pi.
Circle Digits - A Self-Referential Story
Another piece of constrained poetry by Mike Keith, this time in the shape of a circle, but still with the letter counts of the words spelling out the digits of his favorite number.
Search PI
At this site you can search for a string of digits in pi. Is your birthday in pi?
Marko Nippula's Home Page: Vote on the Future Value of Pi
Eye of the Beholder
This is an interesting story about a possible other universe where there is a pattern in pi and finding it gives meaning to somebody's life.

Links

Pilinks
This is the best one I have seen for sheer number of links.
The Uselessness of Pi and its irrational friends
Also very good.
Links to Pi Pages
This is the links page from the Joy of Pi homepages. It is very nicely done with good descriptions of most of the best pages.
ProsperNet
Liens sympa,...
Pi
Links categorized as technical or non-technical.
Yahoo! Science:Mathematics:Numerical Analysis:Numbers:Specific Numbers:Pi
Links2Go: Formulae for Pi
Links2Go: Constants

Mathematics

The Math Forum Home Page
Mathematical Association of America: MAA Online
Frequently Asked Questions in Mathematics
Yahoo! Science:Mathematics

History of Mathematics

BSHM: WWW Resources
Ancient Geometry and Insights into the History of Mathematics
Clark University History of Mathematics
Trinity College Dublin History of Mathematics
The MacTutor History of Mathematics Archive

Yahoo! Science:Mathematics:History
 
Shelley's Math Articles