## Search found 732 matches

- Thu Apr 01, 2010 1:12 pm UTC
- Forum: Mathematics
- Topic: This Can't Be Right
- Replies:
**8** - Views:
**1397**

### Re: This Can't Be Right

But I will note that 1 is an integer, whereas 1.00000... is a real number. Sure, we can say they have the same value, but they are members of different sets. To justify making such a comparison, we really need to show how the integers are embedded in the reals. Yeeeaaaaaaaaahno, For most purposes, ...

- Thu Apr 01, 2010 1:09 pm UTC
- Forum: Mathematics
- Topic: Ideal Currency Denominations
- Replies:
**47** - Views:
**5812**

### Re: Ideal Currency Denominations

Is it common all over the US for prices to be [nice, round number] + [weird tax percent], or only in certain states/types of store? Is this a common method in many other countries? Yeah, the big problem is that the sales tax level is very fragmented, totally different between states and IME often d...

- Tue Mar 30, 2010 10:30 am UTC
- Forum: Mathematics
- Topic: Math Reference book for Calc and below
- Replies:
**18** - Views:
**1581**

### Re: Math Reference book for Calc and below

I still stand by my recommendation of Calculus: One and Several Variables, but if you're ultimately just looking for reference material rather than something to learn from then that is kind of what the Internet is good at.

- Fri Mar 26, 2010 11:29 am UTC
- Forum: Mathematics
- Topic: Math Reference book for Calc and below
- Replies:
**18** - Views:
**1581**

### Re: Math Reference book for Calc and below

FUN FACT: whenever anything is called [subject][number], no-one has any idea what you're talking about. The curriculum varies massively over every school ever. Anyway, if you're looking for a big book to cover most everything, Calc \mbox{u} lus One And Several Variables published by Wiley basically ...

- Wed Mar 24, 2010 1:39 pm UTC
- Forum: Mathematics
- Topic: Minimisation, ordering and xkcd#173
- Replies:
**9** - Views:
**1852**

### Minimisation, ordering and xkcd#173

Okay I've searched around in the maths forum for a serious look at xkcd#173 , but I couldn't find anything. I was recently reminded of it because of this blog post which is more or less a simplified version of the same thing. The way I figured the problem should go is that there is a bunch of vertic...

- Wed Mar 24, 2010 1:03 pm UTC
- Forum: Mathematics
- Topic: Need a math topic idea
- Replies:
**8** - Views:
**947**

### Re: Need a math topic idea

Is your aim to write about maths, or to write about something that you're applying maths to? Given the choice I'd certainly go for the latter but still involve well written mathematics. Quite how much do you even know? Are you comfortable with differential equations or do you want to stick to straig...

- Wed Mar 24, 2010 12:52 am UTC
- Forum: Mathematics
- Topic: Need a math topic idea
- Replies:
**8** - Views:
**947**

### Re: Need a math topic idea

Population modelling isn't a bad topic to write about. For an overly simplistic model of a single population you could say the the birthrate and deathrate are directly proportional to the current population. i.e. \frac{dP}{dt} = (b-d)P \; | b,d \in ( 0 , 1) . Describe what happens bo...

- Tue Mar 23, 2010 12:47 pm UTC
- Forum: Mathematics
- Topic: So, my dad sent me 30 dollars
- Replies:
**17** - Views:
**3119**

### Re: So, my dad sent me 30 dollars

The Pleasures Of Counting is a good insight into what the hell applied maths actually is. The Road To Reality is more or less all the mathematical physics that you'll ever really care to know.

- Sun Mar 21, 2010 12:18 pm UTC
- Forum: Mathematics
- Topic: HW Help: attractive forces and differential equations.
- Replies:
**0** - Views:
**511**

### HW Help: attractive forces and differential equations.

I'm given a differential equation in terms of u ( \theta ) and F(\cdot) where u=\frac{1}{r} and F is given, so I can get a general solution for u( \theta ) . But the initial conditions that I'm given are in terms of r and the radial and transverse velocities so how can I get ...

- Wed Mar 03, 2010 2:21 pm UTC
- Forum: Mathematics
- Topic: Cartesian Product
- Replies:
**5** - Views:
**853**

### Re: Cartesian Product

But that each one had a point (a,b,c,d) with a,b,c,d belonging to R in the one case and with two of the four belonging to R and the other two belonging to the set of imaginary numbers. Not sure how to express the imaginary numbers as a set other than saying they are (-inf*i,inf*i). Well, we're talk...

- Sun Feb 28, 2010 6:55 pm UTC
- Forum: School
- Topic: Schools of Fools
- Replies:
**125** - Views:
**15056**

### Re: Schools of Fools

It's also worth noting that the education you receive in school is not just limited to the stuff in the book or coming out of the teacher's mouth. There's lessons to learn about social interaction, social groupings and how other people work. These are just as, if not more, useful than the qualifica...

- Sun Feb 28, 2010 1:24 pm UTC
- Forum: School
- Topic: Schools of Fools
- Replies:
**125** - Views:
**15056**

### Re: Schools of Fools

In the United States, schools are mostly stupid. Most people who go to public schools are complete idiots. There are the people care about football and HAIR! There is no way I could make this clear enough - everything that you care about, ever have cared about or ever will care about is no less or ...

- Wed Feb 24, 2010 9:28 pm UTC
- Forum: Mathematics
- Topic: Base pi
- Replies:
**38** - Views:
**12357**

### Re: Base pi

What does e look like in base π? Maybe equally, if e and \pi are algebraically independent, one can't really be expressed in terms of the other. But if they are algebraically dependant then it should be a finite expression. Whether or not e and \pi are algebraically independent is an unsolved quest...

- Wed Feb 24, 2010 6:26 pm UTC
- Forum: Mathematics
- Topic: I think my Stat prof is nuts
- Replies:
**11** - Views:
**1629**

### Re: I think my Stat prof is nuts

I'm guessing it's what I'd call an assessment, any research technique is okay so long as all the work, answers and calculations are your own.

- Wed Feb 24, 2010 4:18 pm UTC
- Forum: Mathematics
- Topic: I think my Stat prof is nuts
- Replies:
**11** - Views:
**1629**

### Re: I think my Stat prof is nuts

If it's open book then look for the variance on Wikipedia, you'll find relevant information in the infobox for the the distribution in question.

- Thu Feb 18, 2010 11:21 am UTC
- Forum: Mathematics
- Topic: Can't Appreciate the Unknown
- Replies:
**18** - Views:
**2278**

### Re: Can't Appreciate the Unknown

I'd say I was somewhere between 14 and 16 when I learned trig in the geometric sense (just bare definitions), but then learned it all again around 16 in the algebraic sense (identities and stuff). But bearing in mind that American schools seem to teach like, other stuff, I don't see much wrong with ...

- Tue Feb 16, 2010 1:21 am UTC
- Forum: Religious Wars
- Topic: religous wars (hipocrites saying we fight for our god)
- Replies:
**11** - Views:
**2983**

### Re: religous wars (hipocrites saying we fight for our god)

it goes against everything that your religion is trying to preach. Not really. Qt preaches that GUI APIs must be sensible, even if they lock out older languages. This is why they use C++ for their API rather than C. Killing people is completely orthogonal to GUI APIs. Qt also preaches "Try rea...

- Mon Feb 15, 2010 11:53 pm UTC
- Forum: Religious Wars
- Topic: religous wars (hipocrites saying we fight for our god)
- Replies:
**11** - Views:
**2983**

### Re: religous wars (hipocrites saying we fight for our god)

GaGa says I'm right.Voice of reason wrote:rant at me all you want, but your god won't think its right

- Mon Feb 15, 2010 12:31 am UTC
- Forum: Mathematics
- Topic: HW Help: reciprocal vectors
- Replies:
**3** - Views:
**853**

### Re: HW Help: reciprocal vectors

The course is called Mathematical Modelling, basically all the background knowledge I have for this question is the basics of vectors - dot products, cross products, equations of lines and planes, linear independence, vector spaces, that's probably about it as far as vectors specifically are concern...

- Sun Feb 14, 2010 6:10 pm UTC
- Forum: General
- Topic: Lucky Ten Thousand (TIL)
- Replies:
**13423** - Views:
**1768116**

### Re: Today You Learned

the_bandersnatch wrote: his rune was basically a penis:

Pointy.

- Sun Feb 14, 2010 3:49 pm UTC
- Forum: Mathematics
- Topic: HW Help: reciprocal vectors
- Replies:
**3** - Views:
**853**

### HW Help: reciprocal vectors

"find the set of vectors reciprocal to the set [this],[that] and [the other]" I'm thinking I must have slept through the class where they explained what those words mean in that context. Google gives me stuff to do with crystallography (wtf?) and latices (which I'm sure aren't something I ...

- Sat Feb 13, 2010 1:10 am UTC
- Forum: General
- Topic: Confessional Shed - I'll keep a look-out
- Replies:
**38049** - Views:
**2848357**

### Re: Confessional Shed - I'll keep a look-out

Confession: I want to take the key to that cupboard and throw it in the river, so as you can't get in that cupboard. If I leave the key in my room, you go in to my room and take it. If I leave it in my bag, you go in to my bag and take it. Then you tell me I should hide it better. Thanks, Mum. Take...

- Fri Feb 12, 2010 8:14 pm UTC
- Forum: Food
- Topic: Noob Drinks
- Replies:
**104** - Views:
**16178**

### Re: Noob Drinks

Hard cider. If you can't get past the taste of more "serious" seeming drinks and don't want people to htink you're in high school when you're 25, order a Woodchuck or a Hornsby's. Trust me. (That scenario has happened, btw) But... cider makes up a large proportion of what I drank during h...

- Thu Feb 11, 2010 9:31 pm UTC
- Forum: Mathematics
- Topic: Wanted to share: 3D Graph Layout Tool
- Replies:
**3** - Views:
**1376**

### Re: Wanted to share: 3D Graph Layout Tool

Okay that looks cool. Can you give a layperson type description on how you decide where to put a node (actually, same question in 2d if that'd lots easier). On an only slightly related related point, trying to look for an IDE that'd help me play I found that there are three languages that could reas...

- Mon Feb 08, 2010 9:18 am UTC
- Forum: Mathematics
- Topic: Discrete math shouldnt be this hard, right?
- Replies:
**20** - Views:
**4181**

### Re: Discrete math shouldnt be this hard, right?

I'm currently doing a philosophy course where there's a whole load of logic notation and truth tables and stuff, and apart from the couple of people who've done reasonable amounts of maths or CS, everyone is finding it pretty difficult - so yeah, logic is kind of hard for most people. I don't see an...

- Wed Feb 03, 2010 11:24 am UTC
- Forum: General
- Topic: Dear Randall
- Replies:
**53** - Views:
**4746**

### Re: Dear Randall

If by gotten rid of you mean I took them all and have them stacked up in my garage, then yes.bigglesworth wrote:I thought they got rid of all the old cloning tanks that had the side effect of making the person gay?

- Tue Feb 02, 2010 2:03 pm UTC
- Forum: Mathematics
- Topic: Is there a name for this? What about formulae?
- Replies:
**10** - Views:
**2044**

### Re: Is there a name for this? What about formulae?

I'm only in Calc 1 -- what makes it quadratic, not exponential? Exponential means it involves a exponent. Typically e^x (which is called the exponential function) but 2^x is exponential as well (and can be written in terms of the exponential function). Quadratic should be self explanatory. Take a l...

- Sat Jan 30, 2010 5:42 pm UTC
- Forum: Mathematics
- Topic: Lowest number spelt with a 'c'
- Replies:
**12** - Views:
**5935**

### Re: Lowest number spelt with a 'c'

One Two Three Four Five Six Seven Eight Nine Alpha Beta Charlie

Two minutes.

Two minutes.

- Fri Jan 29, 2010 5:33 pm UTC
- Forum: Mathematics
- Topic: Is there a name for this? What about formulae?
- Replies:
**10** - Views:
**2044**

### Re: Is there a name for this? What about formulae?

It seems like you're just looking at series (which are sums of sequences). If you have a sequence \{ a_1 , a_2 , a_3 , \dots \} then the sum of the first n entries would be written as \sum_{i=1}^n a_i (pronounced "the sum of a_i from i=1 to n "). There's lots of standard results for these,...

- Fri Jan 29, 2010 7:51 am UTC
- Forum: Mathematics
- Topic: Everyday randomness
- Replies:
**85** - Views:
**9568**

### Re: Everyday randomness

You could, honestly go for a proper pseudorandom number generator and do it with pencil and paper, with a LCG and small co-efficients, a couple of numbers a minute shouldn't be too challenging. Just remember to use a sharp pencil.

- Fri Jan 29, 2010 12:18 am UTC
- Forum: General
- Topic: Actual Drnukenness!
- Replies:
**1358** - Views:
**345505**

### Re: I can't believe it is the next day and I'm still DRNUK

I FOUND THE DRUNK THREAD. GO ME. YEAH. I didn't eat much today but I made up for that with lots of Irn Bru and Smirnoff and the season première of Skins so it's all good. Somehow I managed to post something offensive and then the Internet got slightly angry and stuff. Yeah. That. Going back to the d...

- Thu Jan 28, 2010 11:33 am UTC
- Forum: Mathematics
- Topic: Probability: Number Guessing
- Replies:
**15** - Views:
**3615**

### Re: Probability: Number Guessing

Going for inclusive - the odds of getting it in n guesses is naively speaking \frac{1}{101} + \frac{1}{100} + \frac{1}{99} + \dots + \frac{1}{101-n} . But as the alt text to 628 points out - people's choice of random number isn't exactly random. Avoid extremes like 0 and 100, and avoid 50 at the cen...

- Wed Jan 27, 2010 6:07 pm UTC
- Forum: General
- Topic: Lucky Ten Thousand (TIL)
- Replies:
**13423** - Views:
**1768116**

### Re: Today I Learned

TIL: If I ever go to New York - there is a place I can pay to take a nap, consequently, I have to go to New York.

- Thu Jan 21, 2010 3:29 pm UTC
- Forum: Mathematics
- Topic: Give these Word Problems a Try
- Replies:
**19** - Views:
**1979**

### Re: Give these Word Problems a Try

If you slavishly follow the gaussian elimination algorithm when you row reduce, you'll take a lot longer to get there than someone who's done a few dozen examples by hand. Its one thing to know the algorithm, its another to know how it works so that you can arrive at the destination by a better pat...

- Thu Jan 21, 2010 11:15 am UTC
- Forum: Mathematics
- Topic: Help! I wrote this and now have no idea what it means.
- Replies:
**2** - Views:
**740**

### Re: Help! I wrote this and now have no idea what it means.

Can you remember what textbooks you might have been reading at the time? If you locate part 172.B and read that chapter again then it might shed some light on the issue.

- Thu Jan 21, 2010 11:10 am UTC
- Forum: Mathematics
- Topic: Give these Word Problems a Try
- Replies:
**19** - Views:
**1979**

### Re: Give these Word Problems a Try

I will go with my 1 word answer of "Maple". Failing that, Gaussian elimination is indeed the way to go. That's not really solving them though - it's asking a computer to solve them for you. It's no problem if I program Gaussian myself, no? :wink: The issue is whether you understand the al...

- Wed Jan 13, 2010 3:21 pm UTC
- Forum: Mathematics
- Topic: Mathematics and intellect
- Replies:
**85** - Views:
**9618**

### Re: Mathematics and intellect

Mathsy smart might just be a rarer type of smart than booky smart, making it stand out more.

- Tue Jan 12, 2010 1:17 am UTC
- Forum: Mathematics
- Topic: Bicentric quadrilaterals.
- Replies:
**8** - Views:
**1203**

### Bicentric quadrilaterals.

This was a question that occurred to me whilst idly doodling. Given two circles, one contained in the other - what conditions are needed for there to exist a quadrilateral that is tangential to the inner one and cyclic to the outer one? If the two circles are concentric then it appears to relate to ...

- Sun Jan 10, 2010 12:20 pm UTC
- Forum: General
- Topic: Just so we're clear...
- Replies:
**191** - Views:
**21202**

### Re: Just so we're clear...

If I may clarify my original position, I'd just like to say that I feel xkcd feeds off of the "emperor's new clothes" phenomenon. The comic is indirectly advertised as being a smart-person's comic (Warning: this comic occasionally contains strong language (which may be unsuitable for chil...

- Fri Jan 08, 2010 4:50 pm UTC
- Forum: Science
- Topic: Bladeless fans?
- Replies:
**18** - Views:
**1662**

### Bladeless fans?

Okay so I was just linked to the Dyson Air Multiplier which apparently isn't on the market yet but omigod it looks gorgeous. Now what I don't completely get is how the air is drawn in in the first place, what it looks like is that a regular fan (on it's side) is concealed within the base to draw air...