# Defining a different symbol to be used as a sum-class symbol

If I'm interested in using an arbitrary symbol or character instead of the default sum-class symbols (such as \int, \coprod, etc), solely with the interest of preserving subscripts and superscripts above and below the symbol, how should I proceed?

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– mafp
May 27 '13 at 12:46

Try \DeclareMathOperator*{\foo}{...}. You'll need to load the amsmath package. This makes \foo have "limit-style" subscripts and superscripts.

\documentclass{article}
\usepackage{amsmath}
\usepackage{amsfonts}
\DeclareMathOperator*{\foo}{\maltese}

\begin{document}
$\foo_{i=3}^{6}(f^2(i))$
\end{document}


If you want the symbol to be larger, then just writing \Large\maltese won't work. Instead, you could use:

\DeclareMathOperator*{\foo}{\text{\Large $\maltese$}}


• there's already a \bigoplus that comes in the requisite two sizes, one for in-text, and one for display. for large operators that aren't yet "available", the two-size convention should be observed, so either two different operaters should be defined, or a rather more complicated formulation using \mathchoice (in which sizes appropriate for use in sub/superscripts can also be provided). May 27 '13 at 14:34
• Heh, that's true. I should really have chosen one of the gazillion other symbols available! May 27 '13 at 17:19
• if you want to revise your answer, why don't you try \maltese (from amsfonts). i'm pretty sure that comes in only one size. i was going to suggest \box<something>, but noticed (in the comprehensive symbols list) that \bigbox<something> has actually been concocted for nearly all <something>s. May 27 '13 at 17:27
• +1 Note also that for a one-off use one has the low-level $$\mathop{\wr}\limits_{i=1}^n$$. May 28 '13 at 6:20
• @barbarabeeton I've revised my answer as per your suggestion. Thanks :-). Btw, what's the "proper" way to do this? I mean, how is \Sigma scaled to the right size and vertical position to make a summation symbol, for instance? May 28 '13 at 6:50