You are completely right!

That was my problem, I had a wrong definition of 2-norm in my notes. Using your definition, it works flawlessly.

Thanks!

## Search found 38 matches

- Fri Nov 16, 2012 4:52 pm UTC
- Forum: Mathematics
- Topic: matrix 2-norm?
- Replies:
**2** - Views:
**1946**

- Fri Nov 16, 2012 12:44 pm UTC
- Forum: Mathematics
- Topic: matrix 2-norm?
- Replies:
**2** - Views:
**1946**

### matrix 2-norm?

I'm doing some school work, related to a matlab course, and I'm having some problems regarding the 2-norm of a matrix. I don't understand it quite well, because my results won't fit what's expected. Im supossed to find the 2-condition of a Wilson matrix, which apparently is equal to |||a||| * |||a^-...

- Wed Oct 31, 2012 4:05 am UTC
- Forum: Mathematics
- Topic: Probability exercise: limit of sequence using definition
- Replies:
**7** - Views:
**1390**

### Re: Probability exercise: limit of sequence using definition

What does it mean in terms of the A m to say that a given x-value is in every B n ? I guess it means that m reaches a point (M) where every Am superior to that M contains x (or at least, there are infinite Am superior to M that contain x). Otherwise, it would be possible to find a Bn large enough s...

- Wed Oct 31, 2012 3:22 am UTC
- Forum: Mathematics
- Topic: Probability exercise: limit of sequence using definition
- Replies:
**7** - Views:
**1390**

### Re: Probability exercise: limit of sequence using definition

Oh, ok. So then, what I'm taking as the limit is "what is left" after progressively getting rid of the smaller sets, that is, the sets in the largest numbers of the sequence, right? If that is correct, then what skullturf said is right, and the limit will be -1=< x =< 1. But the main probl...

- Wed Oct 31, 2012 2:50 am UTC
- Forum: Mathematics
- Topic: Probability exercise: limit of sequence using definition
- Replies:
**7** - Views:
**1390**

### Re: Probability exercise: limit of sequence using definition

Yes, I know, but if I understood the definition well, then the limit has to contain all "previous" sets, not the ones closer to the limit. So, for example, for n = 1 there will be a set with x <= 2. And the limit has to contain that, too. In other words, the way I understand it I have to c...

- Wed Oct 31, 2012 1:57 am UTC
- Forum: Mathematics
- Topic: Probability exercise: limit of sequence using definition
- Replies:
**7** - Views:
**1390**

### Probability exercise: limit of sequence using definition

I've got this exercise from my probability classes, and I'm stuck. I could really use some help. I don't want the exercise solved, I just don't know what I'm supposed to do and I would like some guidance; however, I don't have a lot of time since the exercise is supposed to be delivered tomorrow (th...

- Wed Sep 26, 2012 11:35 pm UTC
- Forum: Mathematics
- Topic: Math Books
- Replies:
**378** - Views:
**253031**

### Re: Math Books

So, during next semester my subjects will be probability, methods of numerical analysis, and differential calculus. It's my sophomore year so all of them would be almost from scratch. What books would you recommend as an introduction/complement to those classes? Preferably something more focused on ...

- Thu Sep 20, 2012 1:56 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1110:"Click and Drag"
- Replies:
**595** - Views:
**660508**

### Re: 1110:"Click and Drag"

1n36e ("don't go into the tall grass")? Jurassic Park: The Lost World: The Film? Pokemon. The "tall grass" is the first barrier to exploration in the game (once you get out onto the world map) - while in the tall grass, you get attacked by wild Pokemon. Until you get your first ...

- Thu Sep 20, 2012 1:29 am UTC
- Forum: Serious Business
- Topic: Capital Punishment/Death Penalty [Philosophy]
- Replies:
**92** - Views:
**15973**

### Re: Capital Punishment/Death Penalty [Philosophy]

Now, about your initial question: I think that death penalty is bad because it is an indication that society is going wrong. I mean, the penal system is created mainly with the idea that people can change, and that they can be reformed. If a person behaves in a way that is against society, then the...

- Wed Sep 19, 2012 1:27 am UTC
- Forum: Serious Business
- Topic: The Laffer Curve
- Replies:
**57** - Views:
**20106**

### Re: The Laffer Curve

I think that the conclusion that the Laffer curve argument is wrong, because of what you already said: Once you have a percentage lower than 100%, then working will ALWAYS be better than not working, as there are going to be benefits. People will try to improve their quality of life even if the incr...

- Wed Sep 19, 2012 1:16 am UTC
- Forum: Serious Business
- Topic: Capital Punishment/Death Penalty [Philosophy]
- Replies:
**92** - Views:
**15973**

### Re: Capital Punishment/Death Penalty [Philosophy]

I think no government/state should have the option to kill one of it's citizens because any state is formed by it's citizens entering into a social contract that grants them some kind of benefit over a situation in which there is no state. In exchange for this benefit they give up on some things/po...

- Wed Sep 05, 2012 10:41 pm UTC
- Forum: Serious Business
- Topic: Campaign Finance Reform
- Replies:
**27** - Views:
**7222**

### Re: Campaign Finance Reform

Right now, corporations can affect the result of the elections. However, in my opinion this is not the real problem, but just a consecuence of it. Democracy itself is based on mass opinion. Every person votes, without needing any qualification to do so (aside from basic requirements like being old e...

- Sun Sep 02, 2012 2:16 am UTC
- Forum: Serious Business
- Topic: What’s the best piece of advice you could give to everyone?
- Replies:
**121** - Views:
**28853**

### Re: What’s the best piece of advice you could give to everyo

Last-second-before-posting edit: Im about to go to a funeral, so excuse me if this post has a serious/dark tone. Here comes my advice: Living your life slowly is essentially the same as dying early. Maybe even worse, because you'll have to face remorse about what you've wasted. That may seem too gen...

- Sat Sep 01, 2012 11:43 pm UTC
- Forum: Mathematics
- Topic: Interest-related problems
- Replies:
**9** - Views:
**2439**

### Re: Interest-related problems

Oh, ok, if you think about loans then it makes sense. If you don't mind, I'll post here a last exercise, already solved, just to be sure I've understood everything: A 38 year old man receives 2.000.000€ after winning the lottery. He decides to save it until he retires,so he invests all that money in...

- Sat Sep 01, 2012 4:12 pm UTC
- Forum: Mathematics
- Topic: Interest-related problems
- Replies:
**9** - Views:
**2439**

### Re: Interest-related problems

Those last posts have actually confused me a little... "X% nominal annual interest rate, composed trimestrally" sounds like X is equal to r from our formula where n = 3. Interest is compounded three times a year, each time at a rate equal to X/3. Your true effective annual interest rate is...

- Fri Aug 31, 2012 9:12 pm UTC
- Forum: Mathematics
- Topic: Interest-related problems
- Replies:
**9** - Views:
**2439**

### Re: Interest-related problems

So, then, if I'm told something like "X% nominal annual interest rate, composed trimestrally", that X% is means what my unknow trimestral rate would be, if it were annual instead of trimestral. Is that right?

Also, talking about rates, when it's not specified, I have to assume it's annual?

Also, talking about rates, when it's not specified, I have to assume it's annual?

- Fri Aug 31, 2012 7:35 pm UTC
- Forum: Mathematics
- Topic: Interest-related problems
- Replies:
**9** - Views:
**2439**

### Interest-related problems

Here I am again. I was going to post in my former thread, but this problem is about something completely different so I thought it would be better discussed in a different thread. I'm doing some exercises related about dynamic systems, and its practical uses on financial problems. As I stated in my ...

- Tue Aug 28, 2012 12:45 am UTC
- Forum: School
- Topic: How much does university cost in your country?
- Replies:
**32** - Views:
**41180**

### How much does university cost in your country?

I've always heard that the cost of university varies a lot, especially comparing europe with countries outside the EU, and I'm curious about the real differences, and how much of that idea is a myth. I know that this forums are inhabited by people from a lot of countries, so I though it would be int...

- Mon Aug 27, 2012 8:52 pm UTC
- Forum: Mathematics
- Topic: collection of problems
- Replies:
**10** - Views:
**1731**

### Re: collection of problems

That seems like a good rule.

Ok, thanks to all of you for your help! So far I've managed to solve the rest of the problems without much trouble, if I'm stuck again I'll ask in this thread to avoid cluttering the forum...

Ok, thanks to all of you for your help! So far I've managed to solve the rest of the problems without much trouble, if I'm stuck again I'll ask in this thread to avoid cluttering the forum...

- Mon Aug 27, 2012 4:09 pm UTC
- Forum: Mathematics
- Topic: collection of problems
- Replies:
**10** - Views:
**1731**

### Re: collection of problems

I know (x+1) divides 2,3,4,5,6,7,8,9 and 10. No, you don't. You know that (x+1) is divisible by 2,3,4,5,6,7,8,9 and 10. It's probably just a typo, but mistakes like that can lead to disaster. And as I'm looking for the smaller possible x, intuitively x+1 seems to be mcd(1,2,3,4,5,6,7,8,9); which, l...

- Sun Aug 26, 2012 5:29 pm UTC
- Forum: Mathematics
- Topic: collection of problems
- Replies:
**10** - Views:
**1731**

### Re: collection of problems

because, if x-(n-1) is divisible by n, then [x-(n-1)]+n = x+1 is divisible by n too. But I would like to be able to express that more... formally.

- Sun Aug 26, 2012 3:38 pm UTC
- Forum: Mathematics
- Topic: collection of problems
- Replies:
**10** - Views:
**1731**

### Re: collection of problems

What can you say about (x+1)? I know (x+1) divides 2,3,4,5,6,7,8,9. and 10. And as I'm looking for the smaller possible x, intuitively x+1 seems to be mcd(1,2,3,4,5,6,7,8,9); which, looking at prime factors, should be 2³*3²*5*7= 2520 Thus, x must be 2519 and in fact that number satisfies the requir...

- Sun Aug 26, 2012 12:47 pm UTC
- Forum: General
- Topic: Best comedy pieces
- Replies:
**45** - Views:
**7383**

### Re: stand-up comedy

Well, I was taught British pronunciation in school, and later I improved my English through movies, which were mostly American for obvious reasons (Hollywood), so I'm more or less used to both pronunciations.

I wasn't aware of the existence of that kind of programs. Thanks, I'll look some episodes!

I wasn't aware of the existence of that kind of programs. Thanks, I'll look some episodes!

- Sun Aug 26, 2012 12:29 pm UTC
- Forum: Mathematics
- Topic: collection of problems
- Replies:
**10** - Views:
**1731**

### collection of problems

I'm trying to do some exercises I found on my university's website. They are suppossed to be basic, but some of them are giving me problems, and I'm worried about it because they shouldn't, as they are aimed to the 1st course, which I recently passed. I plan to do them all, because I feel I'm way do...

- Sat Aug 25, 2012 5:02 pm UTC
- Forum: General
- Topic: Best comedy pieces
- Replies:
**45** - Views:
**7383**

### stand-up comedy

I didn't know whether to put this here or in the tv/movies forum, so I'm sorry if this is not the correct place. I like stand-up comedy, but most comedians I know are Spanish speakers. Recently, I saw one show by Dave Chappelle and I liked it, so I would really like some recomendations. I didn't see...

- Sat Aug 25, 2012 11:49 am UTC
- Forum: Language/Linguistics
- Topic: Odd possessive pronouns
- Replies:
**23** - Views:
**7495**

### Re: Odd possessive pronouns

Question: If we were talking about something genderless but sentient (say, a robot, or whatever); would it be right to use constructions like "the house was its"? Or does being sentient and human-like require being assigned a gender, in the same way that pet dogs can be referred to as he/s...

- Thu Aug 23, 2012 3:06 pm UTC
- Forum: Language/Linguistics
- Topic: Words common to different languages with different meanings
- Replies:
**69** - Views:
**32018**

### Re: Words common to different languages with different meani

I'm from Spain, and in my last year of high school we had a native English teacher from the US. She didn't speak Spanish quite well, to be honest. One day, she told us that she just had an embarrassing moment in a shop. She asked for "carne sin preservativos". She wanted to ask for meat wi...

- Thu Aug 23, 2012 2:51 pm UTC
- Forum: General
- Topic: Do you Dream?
- Replies:
**33** - Views:
**10428**

### Re: Do you Dream?

Personally, I have periods of time on which I dream a lot and periods on which I can't remember anything. It's pretty irregular, but I've found that I dream a lot more when there are changes in my life. That is, when I'm working more, when I'm dedicating my time to something meaningful, when I'm tra...

- Wed Aug 22, 2012 3:08 am UTC
- Forum: General
- Topic: Trying something new every month
- Replies:
**15** - Views:
**3096**

### Re: Trying something new every month

Oh, ok. Well, if you want something which doesn't take time nor requires good shape (at all), you can try lucid dreaming

- Tue Aug 21, 2012 10:23 pm UTC
- Forum: General
- Topic: Show the world your desktop! [Mommy, what's 56K?]
- Replies:
**2356** - Views:
**412944**

### Re: Show the world your desktop! [Mommy, what's 56K?]

Simple, clean and mac-themed. I really like apple's graphic style, but I find ubuntu more functional.

- Tue Aug 21, 2012 6:48 pm UTC
- Forum: Mathematics
- Topic: synonyms for "solve for x" or "isolate x"
- Replies:
**9** - Views:
**3616**

### Re: synonyms for "solve for x" or "isolate x"

In spanish we use the ones you said, and sometimes "encontrar x" (find x). Is that the synonym you were looking for?

- Tue Aug 21, 2012 3:30 am UTC
- Forum: General
- Topic: Trying something new every month
- Replies:
**15** - Views:
**3096**

### Re: Trying something new every month

What about martial arts? I've never been a sports guy, but I would recommend you judo, I tried for just a month and decided to stay. You don't require any previous physical training, as it's more about technique than strenght, and its really addicting. Where I live classes are quite cheap, I pay 20 ...

- Tue Aug 21, 2012 2:09 am UTC
- Forum: Mathematics
- Topic: Problems for Freshpeople
- Replies:
**9** - Views:
**1959**

### Re: Problems for Freshpeople

I've been a freshman this past course. I live in Spain, so I'm not going to tell you about specific things that I considered difficult because the first year program is probably quite different there. However, as I stated a couple weeks ago in a different thread, I was left was a feeling of confusio...

- Wed Aug 15, 2012 10:16 pm UTC
- Forum: Mathematics
- Topic: Lost student
- Replies:
**13** - Views:
**4784**

### Re: Lost student

In my university math class, a sequence of four courses appropriately* titled "Advanced Calculus", we derived the formula for determinants from its properties. Good thing I still have my notes! 1. Axioms det n is a function on nxn matrices that gives a number. We want it to have propertie...

- Wed Aug 15, 2012 1:00 am UTC
- Forum: Mathematics
- Topic: Lost student
- Replies:
**13** - Views:
**4784**

### Re: Lost student

So part of the problem is that you are experiencing acceleration. They want to be able to bring you up to competence in a mere 4 years, and they aren't stopping to smell the flowers along the way. And the people teaching you are not holding your hand. They are throwing information at you as fast as...

- Sun Aug 12, 2012 6:26 pm UTC
- Forum: Mathematics
- Topic: Lost student
- Replies:
**13** - Views:
**4784**

### Re: Lost student

Thanks for your responses, both about the determinant's use and about the general idea. Yes, I'm aware that in some cases, and especially in abstract reasoning subjects, sometimes is necessary some practice in order to understand the advanced applications of a concept or idea. And I understand too, ...

- Mon Aug 06, 2012 3:01 pm UTC
- Forum: School
- Topic: The Foreigners' Guide To Chinese Culture
- Replies:
**28** - Views:
**22410**

### Re: The Foreigners' Guide To Chinese Culture

If the thread is not dead yet, i would like to ask some questions, too: How are USA and Europe view in China? Not only the official opinion , but the people 's opinion too. What would you say are the main differences between the western and the eastern way of thinking? (if any) Thanks for your answe...

- Mon Aug 06, 2012 10:55 am UTC
- Forum: Mathematics
- Topic: Lost student
- Replies:
**13** - Views:
**4784**

### Lost student

First things first: Hi to everyone, as this is my first post in these forums :D Also, excuse my English if it's not quite correct, it's not my native language. I live in Spain, and this last course I started studying a degree in mathematics and statistics (that's how it's called here, I don't know w...