# Homework Help: How do you guys write your vectors?

1. Jan 16, 2013

### eurekameh

In introductory physics and lower-level engineering courses, my professors would write their vectors with arrowheads on top. Now, I'm starting to see them being underlined a lot more. Why is this? Personally, I still like the arrowheads on top convention, but I can start underlining them if it would be beneficial in the long run.

2. Jan 16, 2013

### FeynmanIsCool

Well, in texts it is usually bold such as "vector R" but I don't think there is a "correct" way. Ive seen over line, over arrow, under line, Bold, and left side lines (connected to letter)Most professors use over the top arrow since its easiest to denote (much easier then trying to make a letter bold!) But Richard Feynman is his "Lectures on Physics" explained all the many ways to denote, and ended it with "You can invent your own!" (pg 22 Vol II)

3. Jan 17, 2013

### jhae2.718

By hand, arbitrary vectors with underbar, unit vectors underbar with hat, e.g.
$$\ddot{\underline r} = \left(\ddot{r} - r\dot{\theta}^2\right) \hat{\underline e}_r + \left(r\ddot{\theta} + 2\dot{r}\dot{\theta}\right)\hat{\underline e}_\theta$$

Using $\LaTeX$, bold italic (\usepackage{bm} and \renewcommand{\vec}[1]{\bm{#1}}), e.g.
$$\ddot{\boldsymbol r} = \left(\ddot{r} - r\dot{\theta}^2\right) \hat{\boldsymbol e}_r + \left(r\ddot{\theta} + 2\dot{r}\dot{\theta}\right)\hat{\boldsymbol e}_\theta$$

Last edited: Jan 17, 2013