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General Discussion => Other Discussions => Math and Science => Topic started by: Yeong on March 02, 2011, 05:06:16 pm

Title: Favorite math theory/rules/law/et cetera.
Post by: Yeong on March 02, 2011, 05:06:16 pm
Well, mah favorite math law is L'Hospital's Law.
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: squidgetx on March 02, 2011, 06:35:37 pm
Taylor Series. Just the fact that we can take practically any function and write it as a polynomial is mind-blowing. Not to mention you can use them to prove e^(ix)+1=0, which ties for second for me along with 1+2+3+4...=-1/12
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: Xeda112358 on March 02, 2011, 06:39:08 pm
Both of those are among my favorites, but since I study sequences (both infinite and finite) in my spare time, I think I gotta love things like the Riemann Zeta function... it's also yet another reason to love those Taylor Series ♥
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: Builderboy on March 02, 2011, 06:41:57 pm
1+2+3+4...=-1/12

Remind me again how this can be even remotely possible?  There seems to be no way to get that to work O.O
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: Xeda112358 on March 02, 2011, 06:44:07 pm
Is it 1+2+3+4+... or is it 1-2+3-4+5-6...? I know one of them was proven to be -1/12 and the other to be -1/4
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: Builderboy on March 02, 2011, 06:45:08 pm
My question is, how can 1+2+3+4... ever end up being less than 1??  You are starting with 1 and only adding positive numbers, how can you get negative?  It seems mathematically impossible O.o
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: Deep Toaster on March 02, 2011, 06:46:02 pm
Euler's formula forever. It's actually true.
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: Builderboy on March 02, 2011, 06:47:41 pm
it seems that Eulers formula only deals with trig and complex numbers ??? Can i see some sort of mathematical proof or explanation?
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: phenomist on March 02, 2011, 06:48:20 pm
I think you use Ramanujan sums? Yeah, these funky summation systems (Abel, Cesaro, Euler, etc) give you results like 1+1+1+1+... = -1/2, 1-1+1-1+1-... = 1/2, and 1-2+3-4+5-6+... = 1/4.

Let's add a geometry theorem: Given a hexagon that has an incircle, its opposite diagonals meet at a single point. (Brianchon)
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: Deep Toaster on March 02, 2011, 06:48:44 pm
It's here: http://en.wikipedia.org/wiki/Euler's_formula#Proofs It makes no sense, but apparently it makes sense O.o
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: Builderboy on March 02, 2011, 06:52:58 pm
Okay, after doing some reading, it was not fully explained in the original post that it is not a traditional sum, but in fact a Ramanujan Sum, which is *not* the same :P
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: Xeda112358 on March 02, 2011, 06:53:17 pm
That is because even math is theoretical :D
But think of this... when working with mod systems, negatives are really positive. So, say you are working in mod 8... you would count {0,1,2,3,...,6,7,0,1...}...

Now also consider the numbers that are not infinity, but by performing a mathematical operation, you still get that number (so n+a=n, n*a=n, et cetera).

Now say you work in mod r... -1 really equals r-1. Taking all of this into account, working with mod (r) where r is equal to one of the before mentioned "infinite" numbers, the very largest number is in fact -1. No matter how high you count, it has been proven you will never reach these numbers, but in a mod system, -1 means you are just 1 away from that number!

Anywho, that has nothing to do with the proof that 1+2+3+4... is less than 1, but it is still interesting, yes?
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: Builderboy on March 02, 2011, 06:55:50 pm
1+2+3+4... does not equal -1/12.  It eauls -1/12R where R is the symbol denoting a Ramunujan Sum :P
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: AngelFish on March 02, 2011, 07:30:35 pm
-∞(√(x²+y²+z²)e-(x²+y²+z²)))dxdydz =2ㅠ

The reason why is very fun to figure out, but should be rather obvious to some people ;)
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: Yeong on March 02, 2011, 07:32:15 pm
(d/dx)ln x = 1/x

I know this is basic stuff, but without this, there's no complex d/dx ing! XD
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: Hot_Dog on March 02, 2011, 07:34:34 pm
I like Fermat's Last Theorem, as well as the Trapezoid Rule
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: Deep Toaster on March 02, 2011, 09:03:58 pm
-∞(√(x²+y²+z²)e-(x²+y²+z²)))dxdydz =2ㅠ

The reason why is very fun to figure out, but should be rather obvious to some people ;)

I didn't even know there was a triple-integral character O.O

Oh, and vertical integration (for APUSH nerds):


f(x)
dx
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: Builderboy on March 02, 2011, 09:20:28 pm
AP US history ???
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: z80man on March 02, 2011, 09:26:14 pm
1+2+3+4...=-1/12

Remind me again how this can be even remotely possible?  There seems to be no way to get that to work O.O
It seems that you have forgotten that when numbers exceed 32,767 they return to -32,768, therefore allowing a sequence of 1+2+3+4.... to be less than 1. ;)
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: Deep Toaster on March 02, 2011, 11:17:35 pm
Well, it's the same basic idea as those proofs that show 0=1: when you deal with infinite numbers in the wrong way, weird things happen :D

AP US history ???

http://en.wikipedia.org/wiki/Vertical_integration

Like Carnegie's monopoly over the steel industry.
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: ruler501 on March 02, 2011, 11:28:25 pm
I like the fact that from that you can seemingly prove infinity equals negative one half

1+1=1+1+1+1+1+1+1+1+... is an infinity of ones added together so it equals 1*infinity
1+1+1+1+1+1+1+1+1+1+...=-1/2 divide both sides by one and you get infinity equals -1/2
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: willrandship on March 02, 2011, 11:30:45 pm
You didn't do your order of operations ;)
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: yunhua98 on March 03, 2011, 06:12:52 pm
Distributive law.   :P

jk, they're all great.  ;)
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: Juju on March 03, 2011, 06:48:16 pm
I love how Euler's identity includes all the principal mathematical constants in the same formula.

(http://upload.wikimedia.org/math/9/e/9/9e9a547076c6820b95e439dd1a5d6a32.png)
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: jsj795 on March 03, 2011, 07:33:55 pm
(http://img16.imageshack.us/img16/3020/butterflyeffect.png) (http://img16.imageshack.us/i/butterflyeffect.png/)

Buttefly Effect! LOL I don't know what the equation is about, but I love the concept behind the Butterfly Effect
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: Yeong on March 04, 2011, 08:16:24 am
ln (-1)
------  =  Chuck Norris
   0

 :P
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: yunhua98 on March 04, 2011, 09:07:27 am
ln(-1)=(pi)(i)
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: Scipi on March 04, 2011, 07:57:59 pm
Formula for finding prime numbers.

(k + 2)(1 −
[wz + h + j − q]2 −
[(gk + 2g + k + 1)(h + j) + h − z]2 −
[16(k + 1)3(k + 2)(n + 1)2 + 1 − f2]2 −
[2n + p + q + z − e]2 −
[e3(e + 2)(a + 1)2 + 1 − o2]2 −
[(a2 − 1)y2 + 1 − x2]2 −
[16r2y4(a2 − 1) + 1 − u2]2 −
[n + l + v − y]2 −
[(a2 − 1)l2 + 1 − m2]2 −
[ai + k + 1 − l − i]2 −
[((a + u2(u2 − a))2 − 1)(n + 4dy)2 + 1 − (x + cu)2]2 −
[p + l(a − n − 1) + b(2an + 2a − n2 − 2n − 2) − m]2 −
[q + y(a − p − 1) + s(2ap + 2a − p2 − 2p − 2) − x]2 −
[z + pl(a − p) + t(2ap − p2 − 1) − pm]2)
> 0

Strangely enough I made a program on calc and computer that use this formula but I never got it to work. :(
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: Hot_Dog on March 04, 2011, 08:16:10 pm
I don't know who discovered this equation, but I call it the "mosquito curve" and I found it by accident.  (This is in polar graphing)

r = sin(cos(tan(theta)))
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: phenomist on March 04, 2011, 09:13:56 pm
Formula for finding prime numbers.

(k + 2)(1 −
[wz + h + j − q]2 −
[(gk + 2g + k + 1)(h + j) + h − z]2 −
[16(k + 1)3(k + 2)(n + 1)2 + 1 − f2]2 −
[2n + p + q + z − e]2 −
[e3(e + 2)(a + 1)2 + 1 − o2]2 −
[(a2 − 1)y2 + 1 − x2]2 −
[16r2y4(a2 − 1) + 1 − u2]2 −
[n + l + v − y]2 −
[(a2 − 1)l2 + 1 − m2]2 −
[ai + k + 1 − l − i]2 −
[((a + u2(u2 − a))2 − 1)(n + 4dy)2 + 1 − (x + cu)2]2 −
[p + l(a − n − 1) + b(2an + 2a − n2 − 2n − 2) − m]2 −
[q + y(a − p − 1) + s(2ap + 2a − p2 − 2p − 2) − x]2 −
[z + pl(a − p) + t(2ap − p2 − 1) − pm]2)
> 0

Strangely enough I made a program on calc and computer that use this formula but I never got it to work. :(

If I remember correctly, k is prime iff there exists a Diophantine solution on the other variables. (aka: practically, this formula is "computationally useless" :P) You'd need to solve for the other 25 or so integer variables such that the inequality holds; not an easy task :P
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: Scipi on March 04, 2011, 09:17:40 pm
So brute forcing it like I was trying to do won't work then. :D
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: Deep Toaster on March 04, 2011, 11:19:40 pm
I don't know who discovered this equation, but I call it the "mosquito curve" and I found it by accident.  (This is in polar graphing)

r = sin(cos(tan(theta)))

Lol, I do that too XD But r=sin(sin(sin(tan(θ is better.

Another fun thing to do is Y=sin(cos(tan(X, change it to Dot mode, then set the window range to (-50,50) and (-1.25,0.75). It's a nearly perfect butterfly O.O
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: Hot_Dog on March 04, 2011, 11:31:27 pm
I don't know who discovered this equation, but I call it the "mosquito curve" and I found it by accident.  (This is in polar graphing)

r = sin(cos(tan(theta)))

Lol, I do that too XD But r=sin(sin(sin(tan(θ is better.

Another fun thing to do is Y=sin(cos(tan(X, change it to Dot mode, then set the window range to (-50,50) and (-1.25,0.75). It's a nearly perfect butterfly O.O

"Nearly" is a good word, because there is an actual "butterfly curve."  (It's called that, too.)  Although I forgot the equation for the butterfly curve.
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: phenomist on March 05, 2011, 12:03:41 am
Here's an interesting prime generating algorithm and a nice programming challenge at the same time (figure out how this works!):

(17/91, 78/85, 19/51, 23/38, 29/33, 77/29, 95/23, 77/19, 1/17, 11/13, 13/11, 15/14, 15/2, 55/1)
Start with the number n=2. Take the one leftmost that, when multiplied to n, gives an integer, and multiply that number to n and replace. Repeat process indefinitely.

The primes will be the exponents of all powers of two after the initialization step :D
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: jnesselr on March 05, 2011, 10:25:54 am
I don't understand that at all, can you give a better example?  You start with n=2, but then what leftmost one?  And when you say "when multiplied to n", do you mean the leftmost one to the nth power?  And why do you "multiplied to n" to get an integer, and then "multiply that number to n".  I don't understand what you're trying to say at all, please give an example.
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: phenomist on March 07, 2011, 12:47:48 am
So,
(17/91, 78/85, 19/51, 23/38, 29/33, 77/29, 95/23, 77/19, 1/17, 11/13, 13/11, 15/14, 15/2, 55/1)
Start with the number n=2. Take the one leftmost that, when multiplied to n, gives an integer, and multiply that number to n and replace. Repeat process indefinitely.

2*(15/2) is the first fraction that gives me an integer when multiplied, Store 15 to n.
15*(55/1) = 825
825*(29/33) = 725
725*(77/29)=1925
1925*(13/11)=2275
2275*(17/91)=425
425*(78/85)=390
390*(11/13)=330
330*(29/33)=290
290*(77/29)=770
Repeating this process gives you
910, 170, 156, 132, 116, 308, 364, 68, 4. 4=2^2. Prime #1 found!
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: Scipi on March 07, 2011, 04:19:10 pm
Ok, I see (actually, wouldn't 55/1 be an integer when multiplied? 55/1*2 = 110
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: phenomist on March 07, 2011, 06:48:40 pm
You pick the leftmost fraction that can give you an integer. Since 15/2 is to the left of 55/1, it has precedence.
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: BOB! on March 07, 2011, 07:55:42 pm
Xn+Yn=Zn..... ;D ;D ;D
Fermats Last Theorem!!!!!!!!!!!!!!!
Okay fine i'm not just showing off i know about it because its actually not a very interesting equation.
I also respect something much easier:1/12+1/22+1/32+....................=PIE2/6.
Its called the Basel (harry potter) series but it was first proven by Yuler.
 
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: AngelFish on March 07, 2011, 07:57:39 pm
*Euler.

Oiler refers to either a various hockey teams, a profession, a ship, or a football team.
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: Tribal on March 07, 2011, 08:22:13 pm
I don't know who discovered this equation, but I call it the "mosquito curve" and I found it by accident.  (This is in polar graphing)

r = sin(cos(tan(theta)))

Lol, I do that too XD But r=sin(sin(sin(tan(θ is better.

Another fun thing to do is Y=sin(cos(tan(X, change it to Dot mode, then set the window range to (-50,50) and (-1.25,0.75). It's a nearly perfect butterfly O.O

Is this a dog with wings?
r=tan(cos(cos(sin(theta^2)^2)^2)^3
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: Deep Toaster on March 07, 2011, 08:51:21 pm
I don't know who discovered this equation, but I call it the "mosquito curve" and I found it by accident.  (This is in polar graphing)

r = sin(cos(tan(theta)))

Lol, I do that too XD But r=sin(sin(sin(tan(θ is better.

Another fun thing to do is Y=sin(cos(tan(X, change it to Dot mode, then set the window range to (-50,50) and (-1.25,0.75). It's a nearly perfect butterfly O.O

Is this a dog with wings?
r=tan(cos(cos(sin(theta^2)^2)^2)^3

Oh the things we do when we're bored :P

The dog doesn't seem to work with me, though. Any particular window settings?
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: Tribal on March 08, 2011, 09:57:48 am
I don't know who discovered this equation, but I call it the "mosquito curve" and I found it by accident.  (This is in polar graphing)

r = sin(cos(tan(theta)))

Lol, I do that too XD But r=sin(sin(sin(tan(θ is better.

Another fun thing to do is Y=sin(cos(tan(X, change it to Dot mode, then set the window range to (-50,50) and (-1.25,0.75). It's a nearly perfect butterfly O.O

Is this a dog with wings?
r=tan(cos(cos(sin(theta^2)^2)^2)^3

Oh the things we do when we're bored :P

The dog doesn't seem to work with me, though. Any particular window settings?

No, I just hit ZStandard and it comes up.
It might just be a side view of Hot Dog's mosquito though :P
Title: Re: Favorite math theory/rules/law/et cetera.
Post by: Freyaday on March 08, 2011, 10:06:09 am
Euler's.