2

I would like to type convolution of the same function m times:

$\underbrace{g \ast g \ast \ldots \ast g}_{m}$

but I am looking for some more compact for, something like sum or product of m functions. Do you know of something like that?

closed as primarily opinion-based by Werner, Troy, Martin Schröder, Stefan Pinnow, Au101 Dec 25 '17 at 1:40

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. If this question can be reworded to fit the rules in the help center, please edit the question.

2

You can use a circled asterisk, \circledast from amssymb, and also create a custom symbol for convolution big operator for a different notation, like this

enter image description here

\documentclass{article}
\usepackage{amssymb}
\usepackage{graphicx}

\newcommand{\Conv}{%
  \mathop{\scalebox{1.5}{\raisebox{-0.2ex}{$\circledast$}}
  }
}

\begin{document}

\[
g_1 \circledast g_2 \circledast \cdots \circledast g_n=\Conv_{i=1}^{n} g_i
\]

\[
\underbrace{g \circledast g \circledast \cdots \circledast g}_{m}=g^{\circledast m}
\]

\end{document}
  • thanks a lot, I have already made something like this, based on what I was told by others \mathop{\scalebox{1.5}{\raisebox{-0.7ex}{\makebox[0.5\width][r]{$\ast$}}}}\limits^{m}_{l=0} – Avec Dec 26 '17 at 17:14
  • That is a nice solution as well. Thank you for accepting my answer. – Cragfelt Dec 27 '17 at 7:19
3

This seems compact enough:

\documentclass[12pt]{article}
\usepackage{ amsmath}

\begin{document}

\[ \underbrace{g \ast g \ast\dots\ast g}_{m}\stackrel{\text{def}}{=} g^{\ast m} \]%

\end{document} 

enter image description here

  • Why not dots instead of ldots? – daleif Dec 24 '17 at 16:10
  • @daleif: You're right. I didn't change the O.P.'s code since it was asked for a compact notation. – Bernard Dec 24 '17 at 17:46

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