# Using ** instead of ^

I am used to use ** instead of ^.

Is it possible to somehow define macro that would interpret ** as ^?

I know that I can write ** and in the end replace it with ^ but that macro would be much more comfortable.

I have been looking for this few months ago and I discovered that you can redefine sign for superscript, but I only found that I can redefine it with only one sign but not with two.

Thank you

• So what about your usage of ^ when you deal with limits? Do you use ** as well? As in, \sum_{i=0}**n? – Werner Nov 29 '15 at 18:57
• Depending on the editor you're using, shouldn't you be able to define a macro there that changes your ** input into ^ as you type, therefore eliminating the need to redefine any commands? – BMWurm Nov 30 '15 at 11:17

You can do it. Don't.1

\documentclass{article}

\makeatletter
\begingroup\lccode~=* \lowercase{\endgroup\def~}{\wagner@starstar}
\newcommand{\wagner@starstar}{%
\@ifnextchar*{\wagner@superscript}{\wagner@asterisk}%
}
\newcommand{\wagner@superscript}[1]{^}
\mathchardef\wagner@asterisk=\mathcode*
\AtBeginDocument{\mathcode*="8000 }
\makeatother

\begin{document}

$A*B$

$a**2$

$\begin{array}{*{2}{c}} a & b\\ c & d \end{array}$

\end{document}


1 It's true that several languages use ** for denoting exponentiation (but several others use ^). They might also have rules about the interpretation of 2**3**4, which TeX doesn't have and they probably accept 2 ** 12 and this will definitely give the wrong result with TeX. Not because of the spaces, which are basically ignored in math mode, but because 2^{12} is the correct input. You could also be prone to type things like 2**(3+5) that would lead to disaster.

When in Rome, do as the Romans do.

• Making * math active doesn't interfere with other usages of the character as shown with the array environment. – egreg Nov 29 '15 at 19:12
• Out of curiosity, why is the \lowercase trick necessary here? – zwol Nov 29 '15 at 22:26
• @zwol I avoid \gdef whenever possible. – egreg Nov 29 '15 at 22:32
• @BMWurm I've added some reasons. – egreg Nov 30 '15 at 12:49
• I like both the tone and content of egreg 's answer. – JPi Nov 30 '15 at 13:05