Talk:Pi

A-class review

I've nominated this article for A-class review through Wikipedia:WikiProject Mathematics. I'm transcluding it below. Please help me address/respond to their concerns. I'd eventually like to nominate this article for FA. —Disavian (^talk/_contribs) 19:25, 12 December 2007 (UTC)

Baffling and unnessisary links in the External Links section

Such as the pi is wrong! link - amusing and irreverent as this may be, it's utterly unnessisary and reads like the type of dross that me and my friends used to write at the back of Math class when we were 14. It doesn't really deserve a place on this page because it adds nothing to the discussion of what Pi is, does or is useful for. —Preceding unsigned comment added by 87.194.49.123 (talk) 19:00, 4 May 2008 (UTC)

I agree, the links need to be sorted, some just repeat themselves (Bonzai273 (talk) 04:39, 24 May 2008 (UTC))

The "π Is Wrong!" article makes a serious point, and the link to it should be kept. —Preceding unsigned comment added by 86.130.60.154 (talk) 15:55, 6 June 2008 (UTC)

Redirect to Pi

3.1415926535897932384626515 redirects to Pi. Although this is not the actual value of Pi, it may seem so at the beginning, but 515 is to be replaced with 832 (3.1415926535897932384626832795) Androo123 (talk) 00:41, 23 May 2008 (UTC) I eat PI

Hex

Hexadecimal 3.243F6A8885A308D31319, as stated in article does appear as Hex. I have seen Hex. when programming. 0, I believe is a null, the lowest value; not zero as in a number line; and should not appear in a decimal series. Coding of Hex., e.g, on OS MVS/XA uses a letter and number on the bit-map, no series of numbers. Please check. Your table might only apply to ASCII?

ASCII:

http://www.asciitable.com/

EBCDIC:

http://www.legacyj.com/cobol/ebcdic.html

Notice, in EBCDIC there are two for the bit, usually expressed using two lines, one line over the other line. To confirme check with a mainframe system programmer.

Thanks. —Preceding unsigned comment added by 58.110.206.219 (talk • contribs) 11:11, 28 May 2008; moved from Talk:Pi/to do by —Disavian (^talk/_contribs) 02:09, 29 May 2008 (UTC)

0 exists in all bases. The way it's expressed in COBOL is irrelevant to the purposes of this article. —Disavian (^talk/_contribs) 02:11, 29 May 2008 (UTC)

Unsourced addition

I reverted the following addition to the article:

However, by computing this series in a somewhat more clever way by taking the midpoints of partial sums, it can be made to converge much faster. Let

$\pi _{0,1}={\frac {4}{1}},\pi _{0,2}={\frac {4}{1}}-{\frac {4}{3}},\pi _{0,3}={\frac {4}{1}}-{\frac {4}{3}}+{\frac {4}{5}},\pi _{0,4}={\frac {4}{1}}-{\frac {4}{3}}+{\frac {4}{5}}-{\frac {4}{7}},\cdots \!$

and then define

$\pi _{i,j}={\frac {\pi _{i-1,j}+\pi _{i-1,j+1}}{2}}$ for all $i,j\geq 1$

then computing $\pi _{10,10}$ will take similar computation time to computing 150 terms of the original series in a brute force manner, and $\pi _{10,10}=3.141592653\cdots$, correct to 9 decimal places.

As no reference is given, this appears to be original research. If someone can find a source, please feel free to re-instate with reference. Gandalf61 (talk) 19:48, 31 May 2008 (UTC)

It is somewhat OR in that I'm not sure whether it has ever been published. I posted an article giving this result on Usenet many years ago--you can find it by going to Google Groups and searching on "ash@sumex-aim.stanford.edu sci.math". I sent a proof via private email to Noam Elkies; we agreed that the result is valid and I'm trying to ping Noam now to see if he remembers the correspondence or can point us to a published reference.--Dash77 (talk) 20:45, 31 May 2008 (UTC)

Per a note from Noam, it appears that this is not OR but is an example of the Van Wijngaarden transformation. I am about to reinstate the deleted text with a link to that Wikipedia article, which in turn contains a link to another article that is well referenced.--Dash77 (talk) 01:05, 1 June 2008 (UTC)

Avoid peacock terms

As my simple edit ( http://en.wikipedia.org/w/index.php?title=Pi&diff=216691447&oldid=216456829 ) was reverted by someone who 'disagreed'. Allow me to explain. I didn't state than I don't think Pi is 'important', just that claiming 'importantance' is not, by itself, encyclopedic.

Please refer to Wikipedia:Avoid_peacock_terms

I leave it to someone else to now be bold.

Dr. Zed (talk) 17:58, 6 June 2008 (UTC)

In this case, the term is justified because it has been often said; so I copied the source from e for it. Dicklyon (talk) 00:10, 7 June 2008 (UTC)

Question about not being immediately obvious

"While that series is easy to write and calculate, it is not immediately obvious why it yields π." - in the discussion of 4/1 - 4/3 + 4/5 - 4/7

Why does it say this? The result is easily derived from the expansion of arctanx. I will add this in unless someone objects. Helenginn (talk) 16:32, 7 June 2008 (UTC)

SVG

For anyone who can be bothered, it would be good to replace the gif at the top with an SVG. —[semicolons]— 21:18, 14 June 2008 (UTC)

Pi calced at 3 when figuring the circ/dia ratio of a thin walled vessel.

Wrong. That would make Pi exceed 3.14. As wall thickness increases, the ratio goes up, not down. —Preceding unsigned comment added by 69.122.62.231 (talk) 15:59, 18 June 2008 (UTC)

Pi cropcircle

As the aricle is locked, I'll add it here: Crop circle repesenting pi 86.150.97.50 (talk) 17:13, 20 June 2008 (UTC)