## Search found 122 matches

Sat Feb 08, 2014 11:36 pm UTC
Forum: Mathematics
Topic: One divided by Zero (1/0)
Replies: 44
Views: 8039

### Re: One divided by Zero (1/0)

Please tell me "the reasons it's undefined." These reasons are what I'm arguing against, yet no one has told me them, so how could I possibly disprove them?! That was meant to be the major purpose of this thread! I did tell you, it is because of fields axioms Wait, but wouldn't that mean ...
Sat Feb 08, 2014 10:34 pm UTC
Forum: Mathematics
Topic: One divided by Zero (1/0)
Replies: 44
Views: 8039

### Re: One divided by Zero (1/0)

R is defined as the unique (up to isomorphism) archimedean, complete and ordered field. The unique, etc. field? Doesn't the set of rational numbers follow those properties? No, the field of rationals is ordered and archimedean, but it isn't complete. For a field to be archimedean it must not contai...
Sat Feb 08, 2014 10:00 pm UTC
Forum: Mathematics
Topic: One divided by Zero (1/0)
Replies: 44
Views: 8039

### Re: One divided by Zero (1/0)

Could you demonstrate how ∞ violates such axioms? Also, how am I evaluating ∞ within the field of reals (which I assume you are implying)? Is it because I use 'real operations'? R is defined as the unique (up to isomorphism) archimedean, complete and ordered field. For a field to be archimedean it ...
Sat Feb 08, 2014 4:33 pm UTC
Forum: Mathematics
Topic: One divided by Zero (1/0)
Replies: 44
Views: 8039

### Re: One divided by Zero (1/0)

1) How is it not a real number? 2) How does it not being a 'real number' make it so I can't use it like such? Have a good day! 1)∞ is not a real number because our definition of real numbers doesn't allow for it be inside the set of real, ∞+1 is an expression as meaningless as §+1, you're adding a ...
Sat Feb 08, 2014 12:47 pm UTC
Forum: Mathematics
Topic: formal logic and similar topics
Replies: 8
Views: 2886

### Re: formal logic and similar topics

I was more interested in a mathematical point of view than a computer science one even though that book sounds very interesting. The problem is that I've read about Gödel and formal systems but I don't know exactly what is the field of mathematics dealing with this things so I don't know what should...
Sat Feb 08, 2014 11:49 am UTC
Forum: Mathematics
Topic: formal logic and similar topics
Replies: 8
Views: 2886

### formal logic and similar topics

I've been reading about formal systems and formal logic (gödel's incompleteness theorem, lambda calculus, curry-howard and such) since they were named and more or less explained in a book I was reading but I'd like to read something more specific about these topics since I found them extremely inter...
Tue Feb 04, 2014 9:27 pm UTC
Forum: Mathematics
Topic: almost homework, a system in 3 unknowns
Replies: 11
Views: 3147

### Re: almost homework, a system in 3 unknowns

the original excercise was about a polynomial and his roots so I obtained those equations from a cubic polynomial, following your suggestion would bring me back where I started
Tue Feb 04, 2014 7:09 pm UTC
Forum: Mathematics
Topic: almost homework, a system in 3 unknowns
Replies: 11
Views: 3147

### almost homework, a system in 3 unknowns

I was doing a very easy homework question (that I have solved in the "normal" way) when I thought of an alternative solution but I got stuck when I found myself facing a system of 3 equations in 3 unknowns since I have no idea on how to deal with it (unless the equations are linear, but th...
Sat Jan 11, 2014 10:32 pm UTC
Forum: Mathematics
Topic: integer valued polynomial through some points
Replies: 11
Views: 2750

### Re: integer valued polynomial through some points

I have already looked into interpoling polynomials but the coordinates of my points have gaps of several thousands, besides even making up data for all the intermediate values (obtaining a not very handy polynomial of ~8000th degree) I have no guarantee that the polynomial will be integer valued for...
Sat Jan 11, 2014 8:32 pm UTC
Forum: Mathematics
Topic: integer valued polynomial through some points
Replies: 11
Views: 2750

### Re: integer valued polynomial through some points

I have some points with integer coordinates and I need to construct a polynomial passing through those points *and* being integer valued at every other integer, is there a generic way to solve this problem?
Sat Jan 11, 2014 7:41 pm UTC
Forum: Mathematics
Topic: integer valued polynomial through some points
Replies: 11
Views: 2750

### Re: integer valued polynomial through some points

This are indeed very interesting questions, but that isn't what I was asking for, I'm looking for a polynomial with real coefficents that assumes an integer value for every integer input, for example ½x²+½x is an integer valued polynomial even though it doesn't have integer coefficents
Sat Jan 11, 2014 5:46 pm UTC
Forum: Coding
Topic: Bugs popping up only under optimization
Replies: 25
Views: 8278

### Re: Bugs popping up only under optimization

Note that the entire x87 floating point system has been deprecated by Intel after the Pentium2/3 systems and by AMD shortly thereafter. Use the SSE/2/3/4 instructions (which are 64 bits) for anything running on remotely current hardware. Now that you pointed it out what surprises me is that with -O...
Sat Jan 11, 2014 5:00 pm UTC
Forum: Mathematics
Topic: integer valued polynomial through some points
Replies: 11
Views: 2750

### integer valued polynomial through some points

After a discussion in another forum I've been wondering if there is a way to construct an integer valued polynomial passing through a set of given points (with integer coordinates), I searched a bit on the web without finding anything, any hint?
Sat Jan 11, 2014 6:56 am UTC
Forum: Coding
Topic: Bugs popping up only under optimization
Replies: 25
Views: 8278

### Re: Bugs popping up only under optimization

Oh I've got a good one. To start with, here is a fun fact: The floating point registers on x86 are 80 bits wide. That is because intel decided to use an extended format (IEEE 754 if I remember correctly) and not the "usual" 64 bit double precision format to have better accuracy in calcula...
Wed Nov 27, 2013 3:27 pm UTC
Forum: Mathematics
Topic: comparing big numbers by hand
Replies: 7
Views: 1902

### Re: comparing big numbers by hand

I had tried something similar, by trying to calculate wether 5(log(46)-log(55)) is bigger or smaller then 0 by turning it into a single log, but I guess I did something wrong later
Wed Nov 27, 2013 1:31 pm UTC
Forum: Mathematics
Topic: comparing big numbers by hand
Replies: 7
Views: 1902

### comparing big numbers by hand

Today there has been a problem solving competition in my school and one of the problems asked to put in increasing order 3 33 , 4 30 and 5 25 . I thought of comparing 33*log(3), 30*log(4) and 25*log(5) but, since the problems had to be solved with pen and paper only, I couldn't get a precise result ...
Sat Nov 02, 2013 5:38 pm UTC
Forum: Logic Puzzles
Topic: The enigma of @YOUGAKUDAN_00
Replies: 31
Views: 18032

### Re: The enigma of @YOUGAKUDAN_00

Anyone tried to interprete these tweets as japanese characters encoded in GB18030 or some other common encoding for oriental languages?
Thu Oct 31, 2013 8:41 am UTC
Forum: Language/Linguistics
Topic: 中文 Garden - Chinese character study game
Replies: 10
Views: 5990

### Re: 中文 Garden - Chinese character study game

This app looks very interesting but on my phone it is incredibly laggy and I have to tap a lot of times for it to respond which makes it pretty much unusable, but I don't know why is it behaving this way.

If that helps you I tried it on a xiaomi m1s with android 4.0.4 and MIUI as rom
Wed Oct 30, 2013 10:02 pm UTC
Forum: Mathematics
Topic: Question-Sum!!
Replies: 7
Views: 1705

### Re: Question-Sum!!

It is probably related to the floating point representation of reals but that should happen only on some particular sums, can you show us exactly which sum(s) are you speaking about?
Tue Oct 29, 2013 6:46 am UTC
Forum: Coding
Topic: How much space does an int-char-int take up?
Replies: 5
Views: 2986

### Re: How much space does an int-char-int take up?

They have already answered your question but depending on your platform you may not even need to align data, if not for performance, while on other architectures (IA-64, for example) unaligned data may cause your program to crash. Do compilers always align data even if unnecessary and with all the o...
Thu Oct 17, 2013 6:11 pm UTC
Forum: Mathematics
Topic: n sided polygon, n < 3
Replies: 35
Views: 6673

### Re: n sided polygon, n < 3

There's no reason to assume that the 180n-360 formula will work in such a geometry, the sum of the internal angles of a triangle isn't 180° in hyperbolic geometry, but this formula holds in euclidan geometry and that is why there's a constrain on n, monogonos have no meaning in euclidean geometry. B...
Thu Oct 17, 2013 5:24 am UTC
Forum: Computer Science
Topic: Examples of Deep Magic
Replies: 8
Views: 10256

### Re: Examples of Deep Magic

Hacker's delight, from Henry S. Warren contains plenty of bit twiddling tricks, some of which look like dark magic, at least to me!
Tue Oct 15, 2013 6:38 pm UTC
Forum: Computer Science
Topic: searching for a book about chess engines
Replies: 2
Views: 3952

### searching for a book about chess engines

I was wondering how hard it actually is to write a chess engine (I have to find an interesting project for my final exams in high school, so I have various months available, I'm mainly required to make something working, without much concern for speed or memory optimizations), so I googled around fo...
Wed Oct 02, 2013 2:18 pm UTC
Forum: Coding
Topic: Coding: Fleeting Thoughts
Replies: 9979
Views: 1980711

### Re: Coding: Fleeting Thoughts

I was doing some project euler's problems in assembly (on an intel processor) when I found out that I cannot load a 32 bit integer from a register on the FPU stack, but I need to move it to a memory location first, anyone knows why I need to do that?
Sat Sep 28, 2013 10:21 am UTC
Forum: Coding
Topic: The Great Programming Language Survey, poll #2: like
Replies: 26
Views: 8871

### Re: The Great Programming Language Survey, poll #2: like

Other:J. I love is extremely concise syntax
Wed Sep 25, 2013 2:02 pm UTC
Forum: Mathematics
Topic: Cardinality of the complex numbers
Replies: 41
Views: 11793

### Re: Cardinality of the complex numbers

I had no problem understanding why |C|=|R 2 |, or that C and R 2 can.be seen as the same set, my problem was understanding why |C|=|R|, but the space-filling curve is really easy to understand and shows how |R 2 |=|R|. But I find cardinal exponentation confusing, I'll try to read your calculations l...
Wed Sep 25, 2013 1:32 pm UTC
Forum: Mathematics
Topic: Cardinality of the complex numbers
Replies: 41
Views: 11793

### Re: Cardinality of the complex numbers

that makes sense, so the cardinality of C actually is the cardinality of R^2, but that's the same as the cardinality of R.
thanks!

Does that generalize to higher dimensions?
Edit:
yes it does, I read the wiki more carefully.
So |R^n|=|R|, regardless of n, right?
Wed Sep 25, 2013 12:48 pm UTC
Forum: Mathematics
Topic: Cardinality of the complex numbers
Replies: 41
Views: 11793

### Cardinality of the complex numbers

Today I read that |C|=|R|, intuitively I would say that |C|=|R^2|, I have no problem understanding why |N|=|Q|<|R| but I don't get why the cardinality of complex numbers is the same as the cardinality of real numbers, can someone explain it to me in a very simple way (I'm only in high school)? Thank...
Tue Sep 24, 2013 2:35 pm UTC
Forum: Mathematics
Topic: Is there any way to take the square root of a matrix?
Replies: 18
Views: 3852

### Re: Is there any way to take the square root of a matrix?

He knows A only in this specific example, but he doesn't know it generally (why would he want to find it otherwise?)
Fri Sep 20, 2013 6:37 pm UTC
Forum: Coding
Topic: Safely executing unkown code
Replies: 23
Views: 5240

### Re: Safely executing unkown code

I don't know much about embedding Lua and Python and I don't know if they can be embedded in a safe but I have some experience with JavaScript. Lua was born to be embedded so it's trivial to embed it, especially in C/C++ programs as for the safety it's supposed to be easily sandboxable, but I never...
Fri Sep 13, 2013 7:16 pm UTC
Forum: Language/Linguistics
Topic: Size-based intensity for written laughs
Replies: 13
Views: 8638

### Re: Size-based intensity for written laughs

Chinese is pretty simple. They have a character for it: 哈 (conveniently pronounced and transliterated "ha"). Its typical use is two of them (哈哈), but it can be reduplicated ad nauseam for longer laughs. Before anyone asks, it's pretty much coincidence that the right hand half looks kind o...
Mon Sep 09, 2013 5:52 pm UTC
Forum: Language/Linguistics
Topic: Translation game
Replies: 7
Views: 4952

### Re: Translation game

Literal translation:
"Santo vapore di polvere da sparo e fumo di pistole!"

Let's translate another proverb:
"Il vino buono sta nella botte piccola"
Mon Sep 09, 2013 5:38 am UTC
Forum: Coding
Topic: Why Python is the best programming language in the world
Replies: 116
Views: 27277

### Re: Why Python is the best programming language in the world

Just a note that if this thread moves from being an excuse to share neat Python snippets to being an actual discussion of "the best programming language in the world", then it's getting moved to RW. Not saying you can't go down that road... but just putting that out there. As I said I did...
Sun Sep 08, 2013 6:17 pm UTC
Forum: Coding
Topic: Why Python is the best programming language in the world
Replies: 116
Views: 27277

### Re: Why Python is the best programming language in the world

What if python isn't the best programming language in the world? I don't want to start a religious war but Lua can do most of the things python does, but faster and with a much smaller interpreter! Of course it cannot do everything python does, especially when it comes to maths computations, and it ...
Mon Sep 02, 2013 6:32 am UTC
Forum: Religious Wars
Topic: Not Equals
Replies: 91
Views: 71057

### Re: Not Equals

Looks like I'm the only one who voted for ~=, I guess nobody else on this board programs a lot in Lua
Fri Aug 30, 2013 7:02 am UTC
Forum: Mathematics
Topic: basic doubt about groups
Replies: 19
Views: 4964

### Re: basic doubt about groups

I understood next to nothing of your last post, and I'm having trouble understanding what exactly is a finitely generated group, wiki wasn't that helpful either, can someone explain this to me?
Thanks!
Wed Aug 21, 2013 6:41 am UTC
Forum: Logic Puzzles
Topic: Secret Santa
Replies: 45
Views: 17690

### Re: Secret Santa

Now I'm terribly curious about the complicate method, can you post it?
Fri Aug 16, 2013 11:22 am UTC
Forum: Mathematics
Topic: When will \$1 be the smallest denomination?
Replies: 51
Views: 10353

### Re: When will \$1 be the smallest denomination?

Prices are still quantised to the cent; Oh dear. Do they do that awful \$19.99 thing there, too, to avoid the psychology of round numbers? I was under the understanding that that was mostly a US thing. Such prices are common here in Italy too, especially on mobile phones, computers, consoles and.sim...
Thu Aug 15, 2013 5:00 pm UTC
Forum: Mathematics
Topic: basic doubt about groups
Replies: 19
Views: 4964

### basic doubt about groups

I'm reading, out of personal interest, an introductory book to abstract algebra and I've just finished the chapter about cyclic groups. The book says every cyclic group is also abelian and also provides a simple proof of this fact but it doesn't say anything about the opposite so I was wondering if ...
Sat Aug 10, 2013 9:13 pm UTC
Forum: Books
Topic: how old is this book?
Replies: 5
Views: 5757

### Re: how old is this book?

On the first page with the actual beginning, is the left page blank? Yes And can you write the first sentences after the letter from December 20th? So we can make sure it´s the version of the text revised in 1787 (it´s not from that time, but maybe they reprinted some versions without the additiona...

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