While correcting a thesis of a colleague I found this:

screenshot of parentheses, relevant source code highlighted

As you can see, the parentheses around the first and the second item differ, however, they're implemented in the exact same manner (see code snippet and highlighted source code respectively).

\left( p+\frac{a\rho ^2}{N^2_{A}} \right) \left(1-\frac{\rho}{N_{a}}b \right) = \frac{\rho}{N_{a}}R\vartheta

Can anyone explain how they come to look different? Is it because of the indices and exponents?

  • Using a standard class and amsmath package, I can't confirm the difference between the parentheses. We need more information
    – user31729
    Nov 8, 2014 at 12:19
  • amsmath and amssymb is used here and the standard class scrreprt. Font package kpfonts.
    – LCsa
    Nov 8, 2014 at 12:30
  • 3
    kpfonts presumably being the decisive information, that's why it's always best to post a complete (small) document that demonstrates the effect, rather than a fragment which may or may not depending on what other code is needed. Nov 8, 2014 at 12:35
  • You're right, I just forgot to mention the font package in my post... :/ Anyways, I accept your answer below.
    – LCsa
    Nov 8, 2014 at 12:38
  • Welcome to TeX.SX! Usually, we don't put a greeting or a “thank you” in our posts. While this might seem strange at first, it is not a sign of lack of politeness, but rather part of our trying to keep everything very concise. Accepting and upvoting answers is the preferred way here to say “thank you” to users who helped you. Nov 9, 2014 at 1:35

1 Answer 1


TeX fonts have a certain number of delimiters in a range of sizes, and then at some point they switch to a scheme that uses a repeatable straight section to make delimiters of arbitrary size. You just happened to hit the tipping point where one delimiter is a fraction over the point at which it switches to the extendable section. Different font sets will switch at different points, depending how many designed delimiter sizes the font has.

  • This is what I expected... In this specific case it would be the best to choose the size manually via \big( etc, I guess?
    – LCsa
    Nov 8, 2014 at 12:31
  • 1
    @LCsa \bigl(....\bigr) with l and r but yes choosing a size manually is probably the easiest thing here (and often improves the horizontal spacing anyway) Nov 8, 2014 at 12:33

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