http://planetmath.org/encyclopedia has a LOT of information on math, and explains it in a simple enough way that you can probably understand it. I had no idea how to use the summation (sigma:) notation, but it explained it well enough for me to write my Pi program.

Think you could send a crypto link my way in payment, lol :P Crypto is one of my weak parts in general programming, and I'm sure it'd help me with making algos better.
Posted on 2006-07-01 18:18:07 by Bobbias
summation is to add up all the terms.
Posted on 2006-07-01 19:55:37 by roticv
But usually you see something like (the forumla I used to aproximate pi), and
Posted on 2006-07-01 20:24:16 by Bobbias
I feel bad intruding this thread and hence polluting it, so I am splitting up the thread and creating a new one.

There's so many different pi formulas to use. http://en.wikipedia.org/wiki/Pi listed alot of various formulas that you can use. As I'm a lazy fellow, I believe I would just use the formula pi/4 = archtan 1 if I have to approximate the value of pi

archtan can be easily calculated using Maclaurin series.

Summation is a simple thing. According to the formula given by you, in pseudo code (forgive me if it look more like C) it will look like

pi = 0
for (k = 0;; k++){
tmp = k! / (2k+1)!!
pi += tmp
}
Posted on 2006-07-01 23:00:48 by roticv
Yep, that's aboiut it, though it takes considerably more lines in ASM, lol.

I've only taken grade 11 math (failed and crap, because I'm lazy and don't apply myself in school :/) so I've never been introduced to the arctan stuff yet.

If I was trying to make a REALLY fast pi generator, I'd use the Ramanujan formula:
Posted on 2006-07-02 02:34:58 by Bobbias
Posted on 2006-07-14 16:31:35 by Dite
Interseting site I must say.. I was thinking abt finding out the nth digit using another pi formula, but i got lazy.  ;)
Posted on 2006-07-15 12:07:56 by roticv
Yeah, I have a program someplace that was supposed to compute pi through however many runs through my algo (first one I posted there), but I've got a stack overflow and I'm too lazy to figure it out, lol.
Posted on 2006-07-15 13:45:54 by Bobbias
arctan(x) = z <==> tan(z) = x

That's all you should know about arctan. It is the inverse function of tan.
Posted on 2006-10-11 05:29:42 by BoR0

I recently posted some code on the pi-hacks newsgroup.  It can calculate PI to 1 million digits in 2.82 seconds on my Athlon 64 2.2.

They have a file section you can download it from.  The name of the file is chud.zip

http://groups.yahoo.com/group/pi-hacks/files/
Posted on 2006-10-11 10:34:24 by mark_larson