How do I access the integral symbol "\int" after renewcommanding "\int" to something else?

Question

I like to define "\int" to be \operatorname{int}, where int refers to the interior automorphism defined by an element of a group.

This is good for me because integrals never appear in my writing... except sometimes they do. Is there a way to access the integral symbol (usually accessed by $\int$) after you renewcommand{\int}{\operatorname{int}} ?

Answer 1

You can use \let. Since you want to redefine \int as an operator, you need to "unassign" it first using \let\int\relax. If you use \renewcommand, you don't have to do this, but if you use \DeclareMathOperator*, you do.

\documentclass{article}

\usepackage{amsmath}

\let\oldint\int\let\int\relax\DeclareMathOperator*{\int}{int}

\begin{document}

Here is $\int_{a=1}$ inline. Also, $\oldint_0^1f(x)$, And also displayed:
\[
\int_{a=1}\qquad\oldint_0^1f(x)
\]

\end{document}

Answer 2

The safest way is to use \NewCommandCopy:

\documentclass{article}
\usepackage{amsmath}

\NewCommandCopy{\INT}{\int}
\renewcommand{\int}{\operatorname{int}}

If you don't have a recent LaTeX, you can use

\let\INT\int

(but it's better to update).

However, I wouldn't do it and rather use a different name, for instance

\DeclareMathOperator{\Int}{int}