# Describing vectors in n dimensions

1. Sep 23, 2011

### Nano-Passion

Recall that A can be broken up into its components x,y, and z. Can You simply add more components to describe any number of dimensions. Where n would be nth dimension?

A=A_x+ A_y+A_z+⋯A_n

2. Sep 23, 2011

### BruceW

What's the square symbol for? And why do you have theoretical physics degree in your status thingy? Do you mean you will someday hope to get such a degree? I'm hoping of doing a theoretical phd someday. I didn't know there was such a thing as a purely theoretical undergraduate degree, if that's what youre talking about?

About the question: If we have a vector A, then it can be written (in some basis) as its components (A1,A2,A3,A4) For a four-dimensional vector, so yeah, there are as many components as there are dimensions.

3. Sep 23, 2011

### Nano-Passion

For PhD I wrote what I'm striving for. Perhaps that isn't what I should do. I'll edit it.

I've only begun my third semester. :)

Edit: What square symbol?

Last edited: Sep 23, 2011
4. Sep 23, 2011

### BruceW

A=A_x+ A_y+A_z+⋯A_n
The symbol ⋯ just before A_n it looks like two horizontal lines..

5. Sep 23, 2011

### Nano-Passion

Oh sorry, that is supposed to be an ellipse (...) that indicates the sequence.

6. Sep 23, 2011

### WannabeNewton

You don't write it that way. The components are relative to a basis as Bruce mentioned. A vector can be represented as a linear combination of components relative to said basis vectors so it would be written compactly as $V = V^{\alpha }\vec{e}_{\alpha }$ where the repeated indices imply summation over all possible values the index can take. So, for example, a vector $V \in \mathbb{R}^{n}$ can be written, when equipped with the Cartesian chart, as $V = V^{x}\vec{e_{x}} + ... + V^{n}\vec{e_{n}}$ where $\vec{e_{x}} = (1, 0, ..., 0)$ and similarly for the other basis vectors.

7. Sep 23, 2011

### Nano-Passion

I have to admit, I am not familiar with that notation. But I will mention that my book stated $A=A_x\widehat{i}+A_y\widehat{j}+A_z\widehat{k}$. Which is why I simply put:

$A=A_x\widehat{i}+A_y\widehat{j}+A_z\widehat{k}+...A_n\widehat{t}$

Last edited: Sep 23, 2011
8. Sep 23, 2011

### WannabeNewton

No that is perfectly correct. It just wasn't in your original post is all.