## Search found 596 matches

- Tue Oct 13, 2009 3:23 am UTC
- Forum: Mathematics
- Topic: An odd group theory questions
- Replies:
**10** - Views:
**1520**

### Re: An odd group theory questions

You've proved that phi1 composed with phi2 is indeed a function from G to G. But your set J isn't just a set of functions from G to G. It's a set of isomorphisms from G to G. So for closure, you need phi1 composed with phi2 to be an isomorphism as well.

- Tue May 12, 2009 9:23 pm UTC
- Forum: Mathematics
- Topic: The Economist article about math jobs
- Replies:
**0** - Views:
**622**

### The Economist article about math jobs

Does anyone remember an article by the Economist in the last couple years, probably the fall of 2008, talking about how employers wanted people with math degrees? One reason they gave was because the degree strongly suggests you can be trained to do whatever they need, if I recall correctly... I've ...

- Mon Mar 09, 2009 5:00 am UTC
- Forum: Mathematics
- Topic: What Linear Algebra Theorem Is This?
- Replies:
**2** - Views:
**1080**

### Re: What Linear Algebra Theorem Is This?

Thank you so much!

- Mon Mar 09, 2009 4:49 am UTC
- Forum: Mathematics
- Topic: Gauss v Euler
- Replies:
**48** - Views:
**16455**

### Re: Gauss v Euler

These two sum up my view on the subject: I always preferred Euler because he's got this player look about him, all blind and shit but entertaining grandchildren whilst working on some math. "Yeah, whatever, don't care, at least now I have less distractions." Gauss is more of a reserved ty...

- Mon Mar 09, 2009 4:19 am UTC
- Forum: Mathematics
- Topic: What Linear Algebra Theorem Is This?
- Replies:
**2** - Views:
**1080**

### What Linear Algebra Theorem Is This?

I was recently told about a theorem in linear algebra, involving the eigenvalues of a matrix over the complex numbers. Apparently given a matrix, one can find open sets in the complex plane (or real line, given a symmetric matrix) such that if there's a set of exactly k of them that intersect (reall...

- Mon Mar 02, 2009 9:56 pm UTC
- Forum: Mathematics
- Topic: Gauss v Euler
- Replies:
**48** - Views:
**16455**

### Princeps Mathematicorum

You know, I can definitely see picking Euler over Gauss. You just have to have never heard of Gauss.

- Sat Feb 14, 2009 8:54 am UTC
- Forum: The Help Desk
- Topic: Converting Adobe Pagemaker 6.5 Documents
- Replies:
**2** - Views:
**490**

### Converting Adobe Pagemaker 6.5 Documents

Does anyone know how to convert .p65 (Adobe Pagemaker 6.5) documents into a format editable by a modern program? I also have the .pdf created by my .p65 source file, but it's hard to find tools to edit pdfs for free without leaving watermarks.

- Sun Nov 30, 2008 4:37 am UTC
- Forum: Mathematics
- Topic: a^b = b^a for integers a,b > 0
- Replies:
**2** - Views:
**1195**

### a^b = b^a for integers a,b > 0

So I think I have a correct answer to the question of which distinct positive integers (a,b) satisfy a b = b a . Did I miss anything here? First, neither a nor b can be 1: assuming wlog b =1 since (a,b) is a solution iff (b,a) is a solution, a 1 =1 b gives a = 1. Therefore if one of ...

- Sat Oct 11, 2008 5:05 pm UTC
- Forum: Mathematics
- Topic: Need help proving a trigometric identity
- Replies:
**11** - Views:
**2739**

### Re: Need help proving a trigometric identity

Perhaps my advice is superfluous, but depending on your level it might be ok to 1) Write everything in terms of sines and cosines 2) Use e^x=cos(x)+i*sin(x) to write everything in terms of exponentials 3) Replace cos(x) by a and sin(x) by b 4) Simplify a fraction! Make sure you remember that i^2=-1 ...

- Thu Oct 09, 2008 5:47 am UTC
- Forum: Mathematics
- Topic: Oh me yarm I GET IT!
- Replies:
**19** - Views:
**2550**

### Re: Oh me yarm I GET IT!

Speaking of which, I got the same sort of feeling when I got why the dx is at the end of the integral. Enlighten me! I still don't quite get what dx or dy mean on their own. dy/dx isn't really a quotient of infinitesimals, the Chain Rule doesn't work because of du cancelling, and S[thing]dx is eith...

- Thu Sep 25, 2008 7:50 am UTC
- Forum: Books
- Topic: David Foster Wallace
- Replies:
**18** - Views:
**3422**

### Re: David Foster Wallace

In Oblivion, I'd skip Mister Squishy at first and move on to the others, then come back to it.

- Mon Sep 22, 2008 5:29 am UTC
- Forum: Books
- Topic: David Foster Wallace
- Replies:
**18** - Views:
**3422**

### Re: David Foster Wallace

Starting is not the trick. The trick, having started, is to stop.

Oh, I guess that could be taken to refer to a few different things.

Good.

Oh, I guess that could be taken to refer to a few different things.

Good.

- Tue Sep 16, 2008 3:45 am UTC
- Forum: Books
- Topic: David Foster Wallace
- Replies:
**18** - Views:
**3422**

### Re: David Foster Wallace

This is not okay. Vonnegut's death didn't hit me nearly as hard as this.Wallace saw so much, so deeply--he was a Goddamn bloody genius and I'd say he made my life very much better than it was, because his writing was just--well, transcendent. Infinite Jest was and still is the best work of fiction I...

- Mon Aug 18, 2008 12:54 am UTC
- Forum: Mathematics
- Topic: How do these punks do it?
- Replies:
**62** - Views:
**7416**

### Re: How do these punks do it?

I find it's better to act as if talent does exist--as if there are people who will surpass me if I work exactly as hard as they do. That makes me work harder than they do, because I hate to lose.

- Sat Aug 16, 2008 7:14 am UTC
- Forum: Mathematics
- Topic: How do these punks do it?
- Replies:
**62** - Views:
**7416**

### Re: How do these punks do it?

Skeptical if there is such a thing as "talent" we should be able to measure it. Can you measure my "talent" in math? Suppose I do better than you thought I could using sheer will power, then what? you "measure" was wrong? That's naive. Does there exist such a thing as ...

- Fri Aug 15, 2008 10:16 pm UTC
- Forum: Mathematics
- Topic: How do these punks do it?
- Replies:
**62** - Views:
**7416**

### Re: How do these punks do it?

@3.14...: I refute your argument thus . Hmm... not quite as dramatic as kicking a stone , but I like it. I would compare learning mathematics to drinking water. Everyone can do it. But there are people who, in all their lives, would never be able to handle drinking from a firehose. They can't hold ...

- Fri Aug 15, 2008 2:22 pm UTC
- Forum: Mathematics
- Topic: I'm looking for a quote
- Replies:
**13** - Views:
**2262**

### Re: I'm looking for a quote

There's "No discovery of mine has made, or is likely to make, for good or ill, the least difference to the amenity of the world." (Wikiquote) Also: "Thank God that number theory is unsullied by applications," and "Here's to pure mathematics! May it never have any use." ...

- Wed Aug 13, 2008 7:35 am UTC
- Forum: Mathematics
- Topic: Notation Question
- Replies:
**9** - Views:
**1877**

### Re: Notation Question

Thanks, but the answer I was looking for was "yes."

- Tue Aug 12, 2008 4:12 am UTC
- Forum: Mathematics
- Topic: Notation Question
- Replies:
**9** - Views:
**1877**

### Re: Notation Question

Okay, cool. Then I'm not missing anything deep here, it's just another way to express concepts I already know. Thank you, everyone.

p.s. does anyone know of books using this notation?

p.s. does anyone know of books using this notation?

- Mon Aug 11, 2008 8:55 am UTC
- Forum: Mathematics
- Topic: Notation Question
- Replies:
**9** - Views:
**1877**

### Notation Question

In this Wikipedia article http://en.wikipedia.org/wiki/Cauchy%27s ... l_equation, the notation f(.) is used. Would someone be kind enough to tell me why?

- Mon Aug 11, 2008 7:40 am UTC
- Forum: Mathematics
- Topic: Favorite math jokes
- Replies:
**1452** - Views:
**483070**

### Re: Favorite math jokes

A man went to the post office to post a fishing rod which was five feet long and all in one piece. He was upset to find that the maximum parcel length the post office would accept was four feet. He solved the problem by placing the fishing rod diagonally in a rectangular box of length four feet and...

- Mon Aug 11, 2008 7:21 am UTC
- Forum: Mathematics
- Topic: Something I've been wondering since 7th grade
- Replies:
**22** - Views:
**4352**

### Re: Something I've been wondering since 7th grade

There's a case to be made that multiplication is not repeated addition. (http://www.maa.org/devlin/devlin_06_08.html). I'm honestly not sure what to make of it yet, but the point he makes is that just because you come up with the same result multiplying and adding doesn't mean that you did the same ...

- Mon Aug 11, 2008 7:10 am UTC
- Forum: Mathematics
- Topic: Find the 6th number
- Replies:
**60** - Views:
**9188**

### Re: Find the 6th number

3263442?

If so, 10650056950806, 113423713055421844361000442, 12864938683278671740537145998360961546653259485195806.

If so, 10650056950806, 113423713055421844361000442, 12864938683278671740537145998360961546653259485195806.

- Tue Aug 05, 2008 5:44 pm UTC
- Forum: Movies and TV Shows
- Topic: Firefly & Serenity (Use Spoilers!)
- Replies:
**918** - Views:
**194537**

### Re: Firefly

Sir_Elderberry wrote:Pathway wrote:Spoiler:Spoiler:

**Spoiler:**

- Mon Aug 04, 2008 8:02 pm UTC
- Forum: Movies and TV Shows
- Topic: Firefly & Serenity (Use Spoilers!)
- Replies:
**918** - Views:
**194537**

### Re: Firefly

**Spoiler:**

- Fri Jul 25, 2008 7:56 am UTC
- Forum: Mathematics
- Topic: Smoke Detector Intervals
- Replies:
**5** - Views:
**1477**

### Re: Smoke Detector Intervals

The last 4 data points there sum to 507. You have:

508 508

508 508

101

407 508

170

371 541

746 746

102

67

34

305 507

Gather more data!

508 508

508 508

101

407 508

170

371 541

746 746

102

67

34

305 507

Gather more data!

- Sun Jul 13, 2008 6:51 pm UTC
- Forum: Mathematics
- Topic: Mathematicians on wikipedia display liberal bias
- Replies:
**35** - Views:
**6015**

### Re: Mathematicians on wikipedia display liberal bias

Oh, come on. It is a wiki. You know what to do.

Btw, if you want to know more, http://rationalwiki.com/wiki/Conservape ... athematics

Btw, if you want to know more, http://rationalwiki.com/wiki/Conservape ... athematics

- Sun Jul 06, 2008 9:40 pm UTC
- Forum: Mathematics
- Topic: 4n + 3 primes
- Replies:
**12** - Views:
**3056**

### Re: 4n + 3 primes

Cauchy wrote:Sums of two squares are precisely those numbers of the form n^{2}p_{1}p_{2}...p_{k}, where n is an integer and each p_{i}is either 2 or a prime one more than a multiple of 4.

Why is that?

- Sun Jul 06, 2008 3:37 pm UTC
- Forum: Mathematics
- Topic: 4n + 3 primes
- Replies:
**12** - Views:
**3056**

### Re: 4n + 3 primes

A square is equal to either 0 or 1, mod 4. If n is even, n = 2s for some integer s. Then n 2 = 4s 2 . That means n 2 = 0 mod 4. If n is odd, n = 2s + 1 for some integer s. Then n 2 = 4s 2 + 4s + 1 = 1 mod 4. Since n is either even or odd, this takes care of all possible n. Now, 4n+3 = 3 mod 4. There...

- Fri Jul 04, 2008 11:41 pm UTC
- Forum: Mathematics
- Topic: Amusing answers to tests
- Replies:
**393** - Views:
**59421**

### Re: Amusing answers to tests

What, so your professor cares about your work? Harsh. I had a congruence to solve on an abstract algebra test once, and it was unique mod 200... You can guess what I did. The only writing on that problem was my answer. Full credit. :) (The same test, there was a problem intended to be solved with Ga...

- Fri Jun 20, 2008 3:07 am UTC
- Forum: Mathematics
- Topic: Cosine for x?
- Replies:
**17** - Views:
**2838**

### Re: Cosine for x?

That is a Taylor expansion. Wikipedia shall serve you well. Use one of the forms for the error term to estimate your error--I recommend the integral term.

- Wed Jun 11, 2008 7:44 pm UTC
- Forum: Mathematics
- Topic: Analysis Textbooks: Rudin vs. Buck
- Replies:
**11** - Views:
**2690**

### Re: Analysis Textbooks: Rudin vs. Buck

Skill of the professor isn't really a big factor. They're both supposed to be pretty bad.

- Wed Jun 11, 2008 4:26 am UTC
- Forum: Mathematics
- Topic: Analysis Textbooks: Rudin vs. Buck
- Replies:
**11** - Views:
**2690**

### Analysis Textbooks: Rudin vs. Buck

Greetings, xkcd! I come to you with a question about analysis textbooks. I am taking an analysis course next semester. There are several different sections, each under a different professor. I've already selected classes for next year, and I chose the professor with the best time slot. I just found ...

- Tue Jun 10, 2008 5:30 am UTC
- Forum: Mathematics
- Topic: Your Axiom of Choice is SILLY
- Replies:
**60** - Views:
**8587**

### Re: Your Axiom of Choice is SILLY

I find that it's easier to reason that any set can be counted, even if it's impractical to do so (or I just don't have the time), but that's where my personal strangeness comes in. This is perfectly normal. If you do much more mathematics, you'll almost certainly get over it. Rather, you'll underst...

- Wed Jun 04, 2008 8:50 am UTC
- Forum: News & Articles
- Topic: Photographs of un-contacted tribe make the news...
- Replies:
**142** - Views:
**11793**

### Re: Photographs of un-contacted tribe make the news...

I'm all about technology, I just don't believe that people necessarily need it to improve their way of life. It improves mine, sure, but I'm an American. I can't really determine what will improve another culture's way of life , and I'm not about to advocate foisting knowledge of the world on a cul...

- Wed Jun 04, 2008 6:30 am UTC
- Forum: News & Articles
- Topic: Bill O'Reilly Rips Into Anti-Gay Lawyer
- Replies:
**65** - Views:
**5986**

### Re: Bill O'Reilly Rips Into Anti-Gay Lawyer

So there is no bias in Colbert's program? No. Which is to say, there is such a bias. Note that this is not the same as saying Colbert is as biased as O'Reilly. Neither is it the same as saying Colbert strays as far from truth as does O'Reilly. No one watches O'Reilly because he is entertaining? No....

- Wed May 28, 2008 4:10 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 0429: "Fantasy"
- Replies:
**81** - Views:
**18206**

### Re: Fantasy

AAAA! TRANSPOSITION! FIX FIX FIX FOR COVERUP

"we way" --> "way we"

I loves me this comic, though.

"we way" --> "way we"

I loves me this comic, though.

- Mon May 26, 2008 3:53 pm UTC
- Forum: Mathematics
- Topic: Algebraically Closed Fields
- Replies:
**2** - Views:
**1007**

### Algebraically Closed Fields

A post in another thread led to the Wikipedia article on algebraically closed fields , which got me thinking. I now have a question. The article states that no finite field is algebraically closed. It also mentions that for infinite fields, R in particular is not algebraically closed. It also provid...

- Mon May 26, 2008 3:19 pm UTC
- Forum: News & Articles
- Topic: XKCD In the New York Times
- Replies:
**21** - Views:
**4797**

### Re: XKCD In the New York Times

It's kind of cute: they're pretending to understand!

- Mon May 19, 2008 8:10 am UTC
- Forum: News & Articles
- Topic: Pres. Bush: Obama like appeasers of Hitler
- Replies:
**40** - Views:
**4935**

### Re: Pres. Bush: Obama like appeasers of Hitler

The best, BEST part of this whole debacle was watching Chris Matthews, renowned tv "news" douchebag, actually call out a republican commentator for being an idiot. From memory (no youtube at work) it went something like: Chris: "Do you actually know what Neville Chamberlain did? The ...