$\text{tr }(PQ)=\displaystyle\sum_{i=i}^{n}\sum_{j=1}^m
\\\text{tr }(QP)=\displaystyle\sum_{i=i}^{n}\sum_{j=1}^m

When I use something like this, the output looks nice, but the breaks between lines look too small due to the size of \left[ and \right]:

enter image description here

Is there a way to add a bit of space between these lines, so \left[ and \right] don't look like they are almost touching?

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    – user30471
    May 3, 2015 at 5:39

1 Answer 1


First, you need at most \displaystyle per line but you are probably better off using \[...\] or an equation environment.

Secondly, to get the spacing right around operators rather than using \text it is better to use


from the amsmath package. Next, I suspect that what you really want here is to put everything into an alignment enviroment such as the align* environment to give:

enter image description here

Notice that the &'s tell latex where to align the two equations.

Finally, and this is a personal preference, I don't like using \left...\right as I think that the operators are usually too large. Instead I use the amsmath \big, \bigg, \Big, \Bigg operators. Here is the complete code.


      \Big[\prod_{i=i}^{n}\prod_{j=1}^m\ p_{ij}q_{ij}\Big]\\
    \Big[\prod_{i=i}^{n}\prod_{j=1}^m q_{ij}p_{ij}\Big]

  • 1
    \Bigl[ and \Bigr], not just \Big. You may also mention \\[<length>]
    – egreg
    May 3, 2015 at 11:09

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