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Currently I'm having to write something like:

enter image description here

I'm writing "q" in the denominator as |\vec{q}| using the "pipe"; is it the proper way to do it?

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up vote 12 down vote accepted

One way to do it is the following.




\frac{\vec{q} \cdot \vec{r}_j}{\abs{\vec{q}\,} \times \abs{\vec{r}_j}}


enter image description here

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A \vec without subscripts immediately followed by a bar clashes with it, so probably \abs{\vec{q}\,} is better. – egreg Mar 13 '13 at 11:27

As far as I'm into LaTeX this is correct. I would put your formular as


So for getting the absolute value typing the pipe | is fine. But do not use the pipe for some expression like

{a \in A | a \notin B}

instead use \mid there.

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You'll get wrong spacing by using |s instead of \lvert and \rvert. – Svend Tveskæg Dec 16 '13 at 4:57

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