What is the correct way of writing the support of a function in math mode?

Question

So far i have been using $\text{supp} u$ but that is very cumbersome and probably wrong, do we have an equivalent of \lim for $\lim$?

You could use in math-mode $\mathrm{supp} u$ . But your question is not very clear. Here there is an example: https://tex.stackexchange.com/questions/448069/fix-ugly-kerning-in-equation-subscript/448070#448070. — Sebastiano, Dec 05 '18 at 11:36
\text is super wrong (too many people misuse \text), define \supp via \DeclareMathOperator\supp{supp} and use \supp or use \newcommand\supp{\mathrm{supp}} if you do not want it to behave as an operator. — daleif, Dec 05 '18 at 11:43

score 8 · Accepted Answer · 2018-12-05T11:51:04.397

What about:

\documentclass{article}
\usepackage{amsmath}

\DeclareMathOperator\supp{supp}

\begin{document}

  $\supp f(x)$

\end{document}

to produce

Note that this requires the amsmath package. Actually, in the preamble of my papers I usually have quite a lot of these so instead I use code like:

\usepackage{etoolbox}% for \forcsvlist

% mathematics operators
\newcommand{\DeclareMyOperator}[1]{%
  \expandafter\DeclareMathOperator\csname #1\endcsname{#1}
}
\forcsvlist{\DeclareMyOperator}{%
   Ext, End, Hom, Ind, Mat,Res,
}

This defines \Ext, \End, ..., \Res. for me.

score 0 · Answer 2 · answered Dec 05 '18 at 11:49

The good think about LaTex is that it offers a lot of sophisticated commands, for instance, you can use:

\documentclass[10pt,a4paper]{article}
\begin{document}
\noindent Some nice options (note that they also include super/sub scripts in them for instance \texttt{\\<one\_of\_the\_command>\_\{your\_subscript\}$^\wedge$\{your\_super\_script\}})
\begin{itemize}
    \item Supremum: $\sup$
\item   Maximum: $\max$
\item   Infimum: $\inf$
\item   Minimum: $\min$
\item   Limits: $\lim$
\item  Sum: $\sum$
\item $\ldots$
\end{itemize}


\end{document}

This is for instance, would give you:

Note that this is just A list. You can do much more than just listed here.

It should be noted, however, that there is no built-in macro for the support of a function, as it is commonly denoted by supp rather than sup. — Circumscribe, Dec 05 '18 at 20:37

What is the correct way of writing the support of a function in math mode?

2 Answers2