I'd like to show parenthesis in equation environment for beamer presentation. I don't know because it not appear.


\usepackage{lmodern} % required to show the problem




%\subsection{First Subsection}
\begin{frame}{Unified Particle Swarm Optimizer - UPSO}
    \setbeamercolor{block title}{fg=white,bg=red!75!black}
    \begin{block}{PSO tradicional}
        PSO tradicional foi proposto por Eberhart, R. C. and Kennedy, J. (1995) e apresenta as seguintes equações:
                v_{i+1} = \omega v_i + r_1c_1 (\bs{lbest_i} - \bs{x_i}) + r_2c_2 (\bs{gbest_i} - \bs{x_i})\\
                x_{i+1} = x_i + v_{i}\\

  • First: Which parantheses do not appear? Second: You may change \newcommand{\bs}{\mathbf} to \newcommand{\bs}[1]{\mathbf{#1}} [\bs and \mathbf are macros, which take an argument, and not switches].
    – Jürgen
    Mar 28, 2017 at 5:00
  • In instance, (\bs{lbest_i} - \bs{x_i}) these parentheses ( and ). Mar 28, 2017 at 5:10
  • This is a miracle. After running your mwe I really get these parentheses. You may have a look into the log-file: Are there any warnings regarding fonts?
    – Jürgen
    Mar 28, 2017 at 5:15
  • Yes, I tried more once and they appeared. But in my real problem still don't appear. Mar 28, 2017 at 5:18
  • The question is if they appear in the code that you provide here. Mar 28, 2017 at 5:20

1 Answer 1


When you change the order of the packages lmodern and MnSymbol to


than you get the parentheses again.

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