## Search found 765 matches

Mon Jun 28, 2010 5:11 pm UTC
Forum: Mathematics
Topic: Modular law for ideals
Replies: 9
Views: 1889

### Re: Modular law for ideals

If a category theoretic proof is what you're after, you'll first want a universal property which characterizes intersections and sums of ideals. Honestly, it's not worth the effort. Just chase through what intersection and sum mean - it will probably be a lot easier.
Fri May 07, 2010 7:42 pm UTC
Forum: Mathematics
Topic: Algebraic Numbers
Replies: 8
Views: 1790

### Re: Algebraic Numbers

A polynomial [imath]m(x)[/imath] is the minimal polynomial for a number [imath]\alpha[/imath] exactly when [imath]\alpha[/imath] is a root and [imath]m(x)[/imath] is irreducible over the relevant field (in our case, [imath]\mathbf{Q}[/imath]).
Tue Jan 26, 2010 1:53 am UTC
Forum: Mathematics
Topic: A subring of the reals???
Replies: 20
Views: 1546

### Re: A subring of the reals???

Remember: [imath]a^xb^x=(ab)^x[/imath]. That includes cases where [imath]x=1/3[/imath] (like you have). With this in mind, just multiply two generic elements and see that the product can be massaged into the desired form.
Fri Nov 13, 2009 5:45 pm UTC
Forum: Religious Wars
Topic: Linux or Windows or Mac OS? Mac or PC? An Interested Convert
Replies: 43
Views: 16219

### Re: Linux or Windows or Mac OS? Mac or PC? An Interested Convert

Operating systems all suck, so I just use a free one . lolwut? Ubuntu, while free, is still an operating system. That said, I'll echo the suggestion to use Ubuntu. As mentioned, it's free and the distro is fairly newbie friendly. Debian which you mentioned is what Ubuntu is based off of, but it's n...
Sun Nov 01, 2009 7:48 pm UTC
Forum: Coding
Topic: C++ style strings
Replies: 8
Views: 807

### Re: C++ style strings

It's not capatalized.

Code: Select all

string Date::getMonthName() const...

not

Code: Select all

String Date::getMonthName() const...
Sat Oct 10, 2009 7:48 pm UTC
Forum: Mathematics
Topic: Trig Problem
Replies: 4
Views: 971

### Re: Trig Problem

Exactly. \sin(\pi/4)=\sin(3\pi/4)=\sin(9\pi/4)=\ldots=\sqrt{2}/2 , but for the inverse to be a function, you can't have \arcsin(\sqrt(2)/2)=\pi/4, 3\pi/4\ldots. , so we take the principle value, which for arcsin, will give you whichever value works in the inte...
Sat Oct 10, 2009 7:29 pm UTC
Forum: Mathematics
Topic: Trig Problem
Replies: 4
Views: 971

### Re: Trig Problem

The inverse trig functions only return the principle value of their input.
Tue Sep 08, 2009 7:00 am UTC
Forum: Mathematics
Topic: Group Theory Clarification
Replies: 4
Views: 912

### Re: Group Theory Clarification

G/H , not G\backslash H . G\backslash H would be the group resulting from their set difference or something (if it's even a group). Using the first isomorphism theorem suggests to me finding a homomorphism \phi such that \ker \phi = H . Then G/H could be 'identified' as the image of \phi .
Tue Sep 01, 2009 3:40 pm UTC
Forum: General
Topic: "How to get" - Google Autofill
Replies: 44
Views: 6154

### Re: "How to get" - Google Autofill

is probably my favorite.

Haha, wow. That is excellent.
Fri Aug 28, 2009 2:49 pm UTC
Forum: Mathematics
Topic: I may have actually made a useful function...
Replies: 20
Views: 2544

### Re: I may have actually made a useful function...

Take it to a professor. They'll help you figure out if it's actually interesting at all, and if it is, what to do with it.
Thu Aug 27, 2009 3:58 pm UTC
Forum: School
Topic: Ways to keep busy in a boring class
Replies: 124
Views: 13826

### Re: Ways to keep busy in a boring class

I also am trying to make a decent proof that e^iπ=-1. I started with an assumption of Euler's law (not sure if that's the right name but it was one of Euler's) (e^ix=cosx+isinx) and am currently in the process of proving that. I've got to prove that the taylor series give e^x. Once I've done that I...
Tue Aug 25, 2009 3:59 pm UTC
Forum: Mathematics
Topic: Question on Gram-Schmidt Process.
Replies: 7
Views: 1071

### Re: Question on Gram-Schmidt Process.

The "multiplication" you're talking about is the dot product. The dot product is done by multiplying together the corresponding components and then adding all these components together. For example, \begin{pmatrix} 1\\2\\3\end{pmatrix} \cdot \begin{pmatrix}4\\-5\\6\end{pmatrix} = (1...
Mon Aug 24, 2009 4:44 pm UTC
Forum: Mathematics
Topic: Volume of a 2D curve
Replies: 3
Views: 952

### Re: Volume of a 2D curve

Yes. The shape you get is called a paraboloid, and it's graph is indeed given by [imath]z=x^2+y^2[/imath].
Sat Aug 15, 2009 10:11 pm UTC
Forum: Music
Topic: What are you listening to?
Replies: 9560
Views: 1145155

### Re: What are you listening to?

Tue Aug 11, 2009 3:22 am UTC
Forum: Coding
Topic: Coding: Fleeting Thoughts
Replies: 9943
Views: 1904781

### Re: Coding: Fleeting Thoughts

I hope you wrote the program in Lisp.
Mon Aug 10, 2009 3:25 pm UTC
Forum: Mathematics
Topic: Math: Fleeting Thoughts
Replies: 427
Views: 139432

### Re: Math: Fleeting Thoughts

Random brain block or something... Can we combine a proof by (strong) induction with a proof by contradiction? That is, can we prove a base case, make an inductive hypothesis, and then contradict the inductive hypothesis? Ah hell, a sketch of my proof might help. I'm proving that successive Fibonacc...
Sun Aug 09, 2009 4:18 am UTC
Forum: The Help Desk
Topic: user writable directory
Replies: 7
Views: 1181

### Re: user writable directory

On a Windows machine, something like the My Documents folder for the current user would work. On Linux, whatever's in the \$HOME variable, usually /home/username.
Fri Aug 07, 2009 4:25 pm UTC
Forum: Music
Topic: What are you listening to?
Replies: 9560
Views: 1145155

### Re: What are you listening to?

Vintersorg - Månskensmän
Fri Aug 07, 2009 4:18 pm UTC
Forum: Coding
Topic: Coding: Fleeting Thoughts
Replies: 9943
Views: 1904781

### Re: Coding: Fleeting Thoughts

Most hex editors I've used don't allow insertion or deletion at all. (It's too easy to do by accident and the file formats people typically use hex editor on aren't safe to shift things around in). Maybe start with just allowing users to overwrite characters without moving them? Well implementing t...
Fri Aug 07, 2009 4:08 am UTC
Forum: Coding
Topic: Coding: Fleeting Thoughts
Replies: 9943
Views: 1904781

### Re: Coding: Fleeting Thoughts

So I've been working on my hex editor lately, and I now have a functioning gui implemented. Yay! My next course of action is to allow the user to actually modify the files, but I'm not sure how to best implement this... Inserting or deleting in place will be hugely inefficient since the file is just...
Thu Aug 06, 2009 10:36 pm UTC
Forum: Religious Wars
Topic: Am I the only one on here that can't stand Python?
Replies: 184
Views: 34935

### Re: Am I the only one on here that can't stand Python?

I can't get into Python either. I've tried it, and I've tried to make myself like it but all to no avail. Ruby on the other hand... Much, much nicer to work with.
Mon Aug 03, 2009 10:28 pm UTC
Forum: Coding
Topic: Interdependent Files (C)
Replies: 2
Views: 617

### Re: Interdependent Files (C)

That first one worked. I could have sworn I tried that, but apparently not. Thanks!
Mon Aug 03, 2009 10:06 pm UTC
Forum: Coding
Topic: Interdependent Files (C)
Replies: 2
Views: 617

### Interdependent Files (C)

Hey all I have some header files that look something like this //file1.h typedef struct blah1_t { // ... blah2 something; } blah1; // file2.h typedef struct blah2_t { // ... (only built in types) } blah2; void function(blah1 *); It won't compile no matter which files I include in each, and if I try ...
Mon Aug 03, 2009 6:19 pm UTC
Forum: Music
Topic: Traditional Music (Indian, Chinese, Iranian, etc)
Replies: 22
Views: 3594

### Re: Traditional Music (Indian, Chinese, Iranian, etc)

a386 wrote:Have you ever heard any Tuvian throat singing? If you haven't you absolutely should find some it's incredible.
Tuvan throat singing is really cool. I saw Huun Huur Tu live a few years back.
Mon Aug 03, 2009 5:01 am UTC
Forum: The Help Desk
Topic: pretty linux music players
Replies: 30
Views: 4411

### Re: pretty linux music players

Jorpho wrote:When I got sick of trying to make Amarok stop crashing, I switched to Wine + Winamp, and was quite pleased.
If you want Winamp for Linux, try something like Audacious which is a pretty decent Winamp clone. It even supports Winamp 2.x skins.
Mon Aug 03, 2009 4:33 am UTC
Forum: The Help Desk
Topic: Sorting Integers using C
Replies: 2
Views: 580

### Re: Sorting Integers using C

In C, the length of an array declared on the stack (which is what all the variables in your code above are) must be known at compilation time. That means you can't do what you want where you ask the user for the length of the array, and then declare it to be that length. To get around this, you shou...
Sun Aug 02, 2009 10:21 pm UTC
Forum: Coding
Topic: Coding: Fleeting Thoughts
Replies: 9943
Views: 1904781

### Re: Coding: Fleeting Thoughts

jaap wrote:I don't think it is specified. That is why there are the fgetpos and fsetpos functions which can handle large files.
Well I need it to get the number of bytes in the file, so I don't think fgetpos will be all that useful.
Sun Aug 02, 2009 9:50 pm UTC
Forum: Coding
Topic: Coding: Fleeting Thoughts
Replies: 9943
Views: 1904781

### Re: Coding: Fleeting Thoughts

I suppose I could just code up a quick test program to find out, but does anyone know what happens if you call ftell() on a file when the current location exceeds the size of a long (the return type)? Does it return a -1, or does it overflow?
Sun Aug 02, 2009 9:20 pm UTC
Forum: Music
Topic: What are you listening to?
Replies: 9560
Views: 1145155

### Re: What are you listening to?

Trollheim's Grott - Experimentation
Sat Aug 01, 2009 3:43 pm UTC
Forum: Mathematics
Topic: log x
Replies: 36
Views: 4328

### Re: log x

I pronounce lg as log. Chances are if I'm using lg, it doesn't matter what base I'm using.
Fri Jul 31, 2009 9:21 pm UTC
Forum: Coding
Topic: What are you working on?
Replies: 45
Views: 4444

### What are you working on?

What project(s) do you currently have on the go? I'm currently working on an ncurses hex editor in C. I've never used the ncurses library before, and documentation for it isn't fantastic making it a bit difficult, but so far I seem to be getting along OK. I just finished the basics of a GUI, so now ...
Thu Jul 30, 2009 7:11 pm UTC
Forum: Coding
Topic: 365 Days of Hello World
Replies: 5
Views: 1358

### Re: 365 Days of Hello World

#define obfuscation is largely uninteresting since most editors have a find and replace feature.
Thu Jul 30, 2009 4:56 pm UTC
Forum: Coding
Topic: Coding: Fleeting Thoughts
Replies: 9943
Views: 1904781

### Re: Coding: Fleeting Thoughts

That's sort of what I figured. I may have a go at it if I feel up to it.
Thu Jul 30, 2009 4:10 pm UTC
Forum: Coding
Topic: Coding: Fleeting Thoughts
Replies: 9943
Views: 1904781

### Re: Coding: Fleeting Thoughts

I just wrote a Brainfuck interpreter! Yay! Sort of makes me want to try writing a Scheme interpreter or something next. On a side note, how would I go about turning my interpreter into a compiler?
Thu Jul 30, 2009 3:42 pm UTC
Forum: Mathematics
Topic: log x
Replies: 36
Views: 4328

### Re: log x

As a side note, how do people here read 'ln'? I generally read it as 'lawn', but I haven't heard many other people read it like that.
Sun Jul 26, 2009 1:48 pm UTC
Forum: Coding
Topic: C - pass by value vs. pass by pointer
Replies: 9
Views: 2981

### Re: C - pass by value vs. pass by pointer

For consistency, when passing a struct to a function I'll only ever pass a pointer to it.
Sat Jul 25, 2009 5:35 pm UTC
Forum: Logic Puzzles
Topic: Uses for blankets (Divergent IQ test sample)
Replies: 18
Views: 4861

### Re: Uses for blankets (Divergent IQ test sample)

EnderSword wrote:Curious how the divergent IQ test would measure this.

Number of responses in a set time? Creativity of responses?
How can you quantify creativity?
Tue Jul 21, 2009 5:01 am UTC
Forum: Mathematics
Topic: Palindromic numbers
Replies: 17
Views: 2208

### Re: Palindromic numbers

I figure there are some interesting qualities of palindromic numbers. In all honesty, no, there aren't. The property of being a palindrome isn't relevant to any "serious" mathematics. Te elaborate a bit, which numbers are palindromic is entirely dependent upon trivial issues such as the b...
Mon Jul 20, 2009 8:02 pm UTC
Forum: Mathematics
Replies: 15
Views: 1512

However, the series does converge if you raise each term to a power greater than one. For example,
$\sum_{k=1}^{\infty} \frac{1}{k^2} = \frac{\pi^2}{6}$
Mon Jul 20, 2009 5:01 pm UTC
Forum: Books
Topic: Books you never finished
Replies: 280
Views: 167712

### Re: Books you never finished

Lord of the Rings - Despite finding the premise of the book legitimately interesting, the plot just progresses so damn slow that I lose interest. I did enjoy The Hobbit though. Neuromancer - Again, the idea of the book is good, but the writing style bugs me. I may give it another go sometime. Great ...