How can i write my own math operator with limits? I want it to look like:
\sum\limits_{e=1}^{m}
but with a capital A (if possible bigger than the normal text) instead of the sum.
Thanks for the help!
[Tex/LaTex] How to create the own math operator with limits
math-modemath-operators
Related Solutions
This does the job nicely I think (thanks karlkoeller for suggesting improvements):
\documentclass[a4paper]{article}
\pagestyle{empty}
\usepackage{amsmath,amsfonts,relsize,graphicx,dsfont}
\makeatletter
\newcommand*\smallR{\mathds{R}} % <-- this is your symbol
\newcommand*\yo@bigR[2]{\text{#2\raisebox{-#1ex}{$\smallR$}}}
\DeclareRobustCommand*\bigR{\mathop{\mathchoice
{\yo@bigR{0.5}{\larger\larger\larger\larger}} % displaystyle
{\yo@bigR{0.4}{\larger\larger}} % textstyle
{\yo@bigR{0.3}{\larger\larger}} % scriptstyle
{\text{\scalebox{1.4}{\raisebox{-0.3ex}{$\smallR$}}}} % scriptscriptstyle
}\displaylimits}
\makeatother
\begin{document}
\begin{equation*}
\begin{bmatrix} x \\ y \\ z \end{bmatrix}_{\substack{\text{some text}\\\text{other text}}}
=
\sum_x\bigR_{\text{sys1}\rightarrow\text{sys2}}
\begin{bmatrix} X \\ Y \\ Z \end{bmatrix}_{\substack{\text{more text}\\\text{also text}}}
\end{equation*}
\centering
\section{In section title $\sum_x\bigR_{\text{sys1}\rightarrow\text{sys2}}$}
Textstyle: \qquad $\sum_x\bigR_{\text{sys1}\rightarrow\text{sys2}}$
Scriptstyle: \qquad $\scriptstyle
\sum_x\bigR_{\text{sys1}\rightarrow\text{sys2}}$
Scriptscriptstyle: \quad $\scriptscriptstyle
\sum_x\bigR_{\text{sys1}\rightarrow\text{sys2}}$
\end{document}
It would somehow work by just using:
\newcommand\bigR{\mathop{\text{\LARGE\raisebox{-0.5ex}{$\mathds{R}$}}}\limits}
The rest of the mess above is to make it work in any environment and possibly in any font size.
A simple solution would be to use the \DeclareMathOperator* command from the amsmath package. The unstarred version places sub- and superscript limits to the right of the operator; the starred version places limits above and below the operator when it is in displaystyle.
\DeclareMathOperator*{\concat}{[} will produce the following results:
You could leave it like that, but for me, the displayed version produces a [ symbol that is too small. Using the scalerel package, you could make the symbol the same size as a \sum symbol:
\DeclareMathOperator*{\concat}{\scalerel*{[}{\sum}}, which will produce the following:
Here is a MWE:
\documentclass{article}
\usepackage{amsmath,scalerel}
%\DeclareMathOperator*{\concat}{[}
\DeclareMathOperator*{\concat}{\scalerel*{[}{\sum}}
\begin{document}
\[
\concat_{n=1}^{\infty} a_n
\]
Inline: $\concat_{n=1}^{\infty} a_n$.
\end{document}
Best Answer
We can scale the symbol to the height plus depth of the summation and then vertically center it with respect to the formula axis.
A simpler but not not scalable version (it won't work in
In this way the "A" will be as large as the
\sumsymbol.An enhanced version, where one can specify a correction factor for the big symbol in display style, as different symbols seem to require different factors.