A lot of the answers I read/get on this site are something like

θ=cos−1⎛⎝axbx+ayby+azbz∥a⃗ ∥∥b⃗ ∥⎞⎠


a⃗ ⋅b⃗ =∥a⃗ ∥∥b⃗ ∥cos(θ)=axbx+ayby+azbz

Edit: I cannot directly seem to copy/paste them in either or know how to make the weird symbols. Please view the link below.

And like, how/where can I learn to read this very much hard-to-read code and turn it into actual mathematics that I can either write on paper or use for java code?

For example, I get that those weird lines are meant to be a vector or sumink, but then he says,

∥a⃗ ∥=a2x+a2y+a2z−−−−−−−−−−√

So yeah, what does that mean? I get the square root thingy, but what is with the A and the tiny x thing, and whats with the two as well? A big A with a tiny 2 and an x by it? What is that meant to mean?

As I say, the above is only an example (You can find it here - How to calculate the 'rotation' between 2 coordinates?), and I keep having this problem time and time over again on this site. The problem being, I have a brilliant answer, but have absolutely zero idea how to actually even read it!

So how/where can I learn to read this stuff?


  • 6
    $\begingroup$ You may need to update your browser. Mathematics is rendered on this site using MathJax, and can be written using TeX markup. If everything works right, you should see the symbols exactly as they would appear in a book. $\endgroup$
    – Emily
    Jun 23, 2014 at 21:45
  • $\begingroup$ I agree with @AustinMohr. Try a different browser; I use Firefox and the page displays fine. $\endgroup$ Jun 23, 2014 at 21:56
  • 2
    $\begingroup$ It sounds like you are having browser issues. This is what that answer looks like on my computer: i.stack.imgur.com/bVltc.png $\endgroup$ Jun 23, 2014 at 22:02
  • 5
    $\begingroup$ A screenshot would be very helpful. $\endgroup$
    – davidlowryduda Mod
    Jun 24, 2014 at 0:59

1 Answer 1


$a_x$ is the name of a number, specifically the first component (the $x$-coordinate) of the vector $\vec a$. The little $_x$ is part of the name, and has no real mathematical significance. The little $^2$ means it's raised to the second power, in other words that it's multiplied with itself.

As for how to make it look the way it does, any math on this site is (or should be) enclosed within dollar signs, so $1+1=2$ becomes $1+1=2$. If you're wondering how to do more fancy stuff there are three ways to find out more. One is to google "latex math commands" or something to that effect.

The second one is to use other's post for what they're worth. Any mathed text can be right clicked, press "Show math as TeX-commands" and see exactly what the author wrote to make it look like it does. The edit link also lets you see the source code.

The third way is an FAQ set up on this site somewhere, but I can never seem to find it when I want to link someone to it. Edit: robjohn added a link as a comment below. Here it is: MathJax basic tutorial and quick reference

  • 4
    $\begingroup$ MathJax basic tutorial and quick reference $\endgroup$
    – robjohn Mod
    Jun 23, 2014 at 22:03
  • $\begingroup$ This doesn't really address your concerns, it's more of a comment, really, but way past the 500 character limit. $\endgroup$
    – Arthur
    Jun 23, 2014 at 22:08
  • $\begingroup$ What do "∥a⃗∥∥b⃗∥" together just like that mean? They are both vectors, so I cannot multiple them together... Sooo, what are they doing? How are they there? ANd how can I divide something by a vector!?? Thanks. P.S. Thanks for the answer. Been very helpful :). $\endgroup$ Jun 23, 2014 at 22:35
  • $\begingroup$ $\vec a$ is a vector. $||\vec a||$ is a number representing the length of $\vec a$. $\endgroup$
    – Arthur
    Jun 23, 2014 at 22:52
  • 3
    $\begingroup$ @user2722083, you might find this page helpful. $\endgroup$ Jun 23, 2014 at 23:27
  • $\begingroup$ @Arthur Right, so I have a Vector3f of 3 coordinates. How does this have a "Length"? I am confused. $\endgroup$ Jun 24, 2014 at 10:33
  • 1
    $\begingroup$ @user2722083 It seems that you're unfamiliar with the notation and definitions, not that the formatting is broken on the page you see. If that's the case, you should get a textbook in the subject you're interested and read about the concepts. $\endgroup$
    – user61527
    Jun 24, 2014 at 15:01

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .