# Hi

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#### Beer w/Straw

• Jr. Member
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• Transcendental Ignorance!
##### Hi
« on: 23/06/2015 13:07:48 »
$$\frac{1}{\frac{1}{0}}=0$$

This is my first post; didn't see an introduction thread.

Are losing theirs and blaming it on you..
http://www.poetryfoundation.org/poem/175772

Anyway, this forum looks like it has a lot of goodies to unearth. Hoping to be content and not get perturbed.

As I'm typing this I believe it may come off as a bit sucky  [] But I guess that's how I kinda feel ATM.

Anyway, how can I upload an avatar? From what I've seen nobody has them, although I hadn't gone through the entire forum yet.

And again, Hi  [] I think I'm a bit happier now.

#### PmbPhy

• Neilep Level Member
• 2788
##### Re: Hi
« Reply #1 on: 23/06/2015 13:14:44 »
Quote from: Beer w/Straw
$$\frac{1}{\frac{1}{0}}=0$$
That expression is meaningless because the denominator contains an undefined term, i.e. 1/0 is undefined because division by zero is undefined. And it's not merely undefined because someone chose not to define it. It's undefined because any attempt to define it leads to meaningless notions somewhere along the line.

Quote from: Beer w/Straw
This is my first post; didn't see an introduction thread.
Welcome to the forum.  []

And no. There are no avatars here.

#### Beer w/Straw

• Jr. Member
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##### Re: Hi
« Reply #2 on: 23/06/2015 13:26:02 »
http://www.wolframalpha.com/input/?i=1%2F%281%2F0%29&lk=4&num=1

http://www.wolframalpha.com/input/?i=1%2F0

But I wasn't using real numbers.

Why doesn't this site have avatars when when it seems to have lots besides?

#### PmbPhy

• Neilep Level Member
• 2788
##### Re: Hi
« Reply #3 on: 23/06/2015 13:59:38 »
Quote from: Beer w/Straw
http://www.wolframalpha.com/input/?i=1%2F%281%2F0%29&lk=4&num=1

http://www.wolframalpha.com/input/?i=1%2F0
Wolfram gave you the wrong answers. They made an error when they treated infinity as a number. Let me clarify;

You wrote 1/(1/0). To evaluate this you need to first reduce 1/0 to a simpler expression or number. Since 1/0 is undefined you can't correctly take another step. Suppose you think that 1/0 actually does equal infinity. Then is 1/0 > 0 or is 1/0 < 0. That is to say is the infinity positive or negative?

Quote from: Beer w/Straw
But I wasn't using real numbers.
Then you really should have made that clear by saying so. Otherwise how were your readers supposed to know that? And if you weren't using real numbers then what were you using, complex numbers? If so then the numbers you wrote down were still real and division isn't defined for anything other than real and complex numbers. And you chose to use www.wolframalpha.com which is only defined for real numbers. At least for what you used as input.

Anyway, why did you start your first post with that and not even comment on why you put it there? What was its purpose anyway?

Quote from: Beer w/Straw
Why doesn't this site have avatars when when it seems to have lots besides?
You'll have to ask the founder of the forum. I imagine its because this is a serious forum and avatars make it less serious given what some people use as avatars.
« Last Edit: 23/06/2015 14:18:24 by PmbPhy »

#### Beer w/Straw

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##### Re: Hi
« Reply #4 on: 23/06/2015 14:53:44 »
MY post was a jumble of things. Didn't know if the TEX command would actually work.

Also having some unrelated things to contend with, so I may make a more thorough response in like three or four hours... And it was complex infinity, not infinity, if that makes any difference to you.
« Last Edit: 23/06/2015 14:55:50 by Beer w/Straw »

#### PmbPhy

• Neilep Level Member
• 2788
##### Re: Hi
« Reply #5 on: 23/06/2015 16:42:08 »
MY post was a jumble of things. Didn't know if the TEX command would actually work.

Also having some unrelated things to contend with, so I may make a more thorough response in like three or four hours... And it was complex infinity, not infinity, if that makes any difference to you.
I know what it is. I looked it up on Wolfram's site. I've never seen it used anywhere else except by them however and I'm a mathematician as well as a physicist. I studied complex analysis as an undergraduate and nowhere did I ever see any text define that term. E.g. use Google to search for it and you won't find it anywhere else.

I just looked it up in the math dictionary:
http://dlx.bookzz.org/genesis/1152000/31765df43415cea3df8c165975d19db7/_as/[Emma_Previato]_Dictionary_of_Applied_Math_for_Eng(Bokos-Z1).pdf

and it wasn't in there.  The term "infinity" really means "unbounded" so whether its unbounded in the complex plane or on the real axis makes no difference.

I don't mean to be petty. I'm just trying to be helpful. When I see someone being careless like that by dividing by zero a warning sign goes up in my mind. Just trying to help, friend. []

#### Beer w/Straw

• Jr. Member
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• Transcendental Ignorance!
##### Re: Hi
« Reply #6 on: 23/06/2015 17:53:08 »
I don't want to quote you, making this thread more quote than text. And yes, I wanted to be provocative with the OP but not controversial.

My PC running Mathematica 10 I wont turn on ATM as the power supply is dirty and want to clean it first. I don't want to risk it blowing up and taking other components with it. I do believe it would render the same output as WolframAlpha from the same input.

Maple 2015 gives me "Error, numeric exception: division by zero" for the input: 1/0 .

With Google "Complex Infinity" I can get a link to a MATLAB definition"

Quote
complexInfinity represents the only non-complex point of the one-point compactification of the complex numbers.

Mathematically, complexInfinity is the north pole of the Riemann sphere, with the unit circle as equator and the point 0 at the south pole.

With respect to arithmetic, complexInfinity behaves like "1/0". In particular, non-zero complex numbers may be multiplied or divided by complexInfinity or 1/ complexInfinity. Adding complexInfinity to a finite number yields again complexInfinity.

With respect to arithmetical operations, complexInfinity is incompatible with the real infinity.

And from Free Dictionary
Quote
Riemann Sphere
(redirected from Complex infinity)
Also found in: Wikipedia.
Riemann sphere
[′rē‚män ‚sfir]
(mathematics)
The two-sphere whose points are identified with all complex numbers by a stereographic projection. Also known as complex sphere.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
http://encyclopedia2.thefreedictionary.com/Complex+infinity

Anyway, I don't have MATLAB, but I'm positive Mathmatica would give me the same answer as WolframAlpha from the same input.

And thank you for your comments. Before my OP I was more distracted with doing my profile -I'm 2012 years old you know!

#### jccc

• Hero Member
• 990
##### Re: Hi
« Reply #7 on: 23/06/2015 18:37:09 »
cool poem

enjoying it much

man drink beer using mouth

#### chiralSPO

• Global Moderator
• Neilep Level Member
• 1913
##### Re: Hi
« Reply #8 on: 23/06/2015 20:02:27 »
if we evaluate this strictly as 1/(1/0) then there is no way to give the answer, but with a little algebraic manipulation (multiplying by another undefinable, 0/0) we do indeed get (0*1)/(1*0/0), which simplifies to 0/1 = 0. However, one must beware, lots of funny things can be shown when dividing by zero (I can prove 1 = 2, and from there any rational number = any other rational number).

Given no context, I agree with pmbphy, that dividing by 0 gives a nonsensical answer, but if there were some context (what type of zero: is this something where the limit approaches zero? or was this zero introduced to an otherwise soluble expression?) then the expression could be evaluated...

Welcome to the forum!

#### PmbPhy

• Neilep Level Member
• 2788
##### Re: Hi
« Reply #9 on: 23/06/2015 20:38:51 »
Quote from: chiralSPO
if we evaluate this strictly as 1/(1/0) then there is no way to give the answer, but with a little algebraic manipulation (multiplying by another undefinable, 0/0) we do indeed get (0*1)/(1*0/0), which simplifies to 0/1 = 0.
What you assumed was 0/0 = 1 which isn't 1, it's undefined. You can't assume that anything divided by itself equals 1 because the division must be well defined, which 0/0 is not.

Quote from: chiralSPO
Given no context, I agree with pmbphy, that dividing by 0 gives a nonsensical answer, but if there were some context (what type of zero: is this something where the limit approaches zero? or was this zero introduced to an otherwise soluble expression?) then the expression could be evaluated...
The only time it makes any sense is when you use limits as you indicated here. Then of course you have to use L'HOpital's rule. The fact that expressions of an indeterminate form don't make any sense and can't be defined is because there are different values that these things can approach in a limit.

#### Beer w/Straw

• Jr. Member
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• Transcendental Ignorance!
##### Re: Hi
« Reply #10 on: 23/06/2015 23:18:00 »
cool poem

enjoying it much

man drink beer using mouth

once i was half drunk trying to showoff, drinking beer with my nose. no straw.

Well, I'm glad you liked the poem.

#### jccc

• Hero Member
• 990
##### Re: Hi
« Reply #11 on: 28/06/2015 03:00:17 »
i want to thank you again, the poem is like a fountain in desert. i drink it many times already, long way to go. if you even find a man like that, i want to know/meet him.

have the courage say your heart?

#### Beer w/Straw

• Jr. Member
• 11
• Transcendental Ignorance!
##### Re: Hi
« Reply #12 on: 08/07/2015 13:44:41 »
I haven't utilized this forum so great thus far. I've been more looking at other fora and reading the smack. Some people I don't rightly know if they are seriously deluded, being dumb on purpose, or just another crank.

[]