Kindle is clever

If you look on amazon.com, there's sections for "book" "electronics" "music" "kindle"

Must have paid a lot for that spot

they're going for the en.wikipedia.org/wiki/Genericized_trademark

You bag one of these and you've won the game

@QED I thought kindle belongs to amazon.com.

Something like that.

So they don't even have to pay for the spot!

That is what I expect.

Do they do harmonic analysis in Sweden? They sure do in Helsinki, but that ain't Sweden 8-) (Sherlock Teuwen).

2 jurors+executioner needed.

heya=)

hi

@QED - Hi, Does proof of 3 have to do with proof of changing of variable formula for 4 or more variable?

well I can't read this

even if it wasn't missing context, I don't think I know about that stuff

@QED - Have you click on the picture again and clink the picture on a seperate window again?

@Victor, I mean, it's half way through a paragraph

"If the theorem is true..." what theorem??

@QED - The part 3 on the top and i think it have to do with the statement on en.wikipedia.org/wiki/…

@QED - Have you get a BS of mathmatics yet?

@Victor As far as I understand there is only a single variable but rather multiple functions.

@TomWijsman - you mean i can't use the chain rule to prove the several veriable version of the theorem?

What do you mean by several variable?

As long as the output of a function can be taken by input of the next function in the chain, the rule should hold.

@TomWijsman - The several vaiable of the changing of variables formula.

@Victor I don't know what is being referred to as theorem given that the theorem is missing for us ("If the theorem is true..." what theorem??)

@Victor I think you are confused between "changing a variable" and "applying a chain of functions on a functions consisting of multiple variables".

@Victor, may be better to just write out the theorem you want a proof of

or is it that you're reading a proof, and parts of it don't make sense?

Anyhow, I'm just a computer science student and these pages look a bit over the top of my head (they explain it a bit more complex than I'm used to), although I did see chain rule and change of variables myself. Just like QED, I'm kinda confused about what your exact question was because I think you are confusing something.

@QED - After a week of thinking, i still can't get the idea on how to prove the changing of the variables formula for several variables

what theorem

@Victor So your question is "Can I use the chain rule to prove that one is able to consistently substitute multiple variables in an expression?"

@QED - Substitution for multiple variables

And of course "If not, is there a different way to proof it?"

@TomWijsman - I am wondering if those page does any help to solve my concern.

Hi! =)

@Victor I think that "changing a variable" is different from "applying a function", hence you can't use the chain rule for your proof.

hi @N3buchadnezzar

Anyone here know anything about plotting functions either in pgf plots or maple?

@Victor, I'm saying that you should write it out as a formal mathematical statement

@QED - :$dv_1\cdots dv_n = |\det(\operatorname{D}\varphi)(u_1, \ldots, u_n)| \, du_1\cdots du_n$

Where the determinant is the jocobian

I think you might write this as $d \bar v = | \det[(D \varphi)(\bar u)]| d \bar u$

@N3buchadnezzar - it is a unit circle, isn't it?

maybe that's neater, not having any $\ldots$s

it's the intersection of the unit circle with z = x + y

So it is a disk =)

@QED - For a math major, you must know how to prove the multivariable changing of variable formula, right?

all I'm really interested in right now is getting a rigorous clear statement of what you want to prove

@QED - Here it is: mathworld.wolfram.com/ChangeofVariablesTheorem.html

By several variables, do you mean changing separate variables by others or do you mean to replace x² by t and then t² by z. Or a mix of both?

@TomWijsman - The later one

I give up

Oh well, I'm out of this, that link hurts me... xD

@Tom, same here haha

@QED - College student really don't have to prove fundalmental results?