4

Following the advice of this question, I created the \itsep symbol:

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

When used with single character sub/super-scripts, it displays properly, like this:

a \itsep^f_{g} b

correct output

If I place multiple characters in the sub-script the symbol behaves incorrectly:

a \itsep^f_{g \, a \, b} b

incorrect output

Is there a way to make this symbol truly behave like \sum or \bigwedge where the "big" symbol is centered over the subscript and centered under the superscript?

Community
  • 1
Arlen Cox
  • 582

2 Answers2

9

if, instead of using the basic \mathop you use \DeclareMathOperator* from amsmath, this "insulates" the result from its context:

\DeclareMathOperator*{\itsep}{\scalebox{1.5}{\raisebox{-0.2ex}{$\circledast$}}}

thus

\[
a \itsep^f_{g} b \qquad a \itsep^f_{g \, a \, b} b 
\]

results in

enter image description here

barbara beeton
  • 88,848
1

For reference, mathtools provides \mathclap which allows for zero-width centred overlap of math content, based on the size its used in:

enter image description here

\documentclass{article}
\usepackage{mathtools}% http://ctan.org/pkg/mathtools
\usepackage{amssymb}% http://ctan.org/pkg/amssymb
\usepackage{graphicx}% http://ctan.org/pkg/graphicx
\begin{document}
\newcommand{\itsep}{\mathop{\scalebox{1.5}{\raisebox{-0.2ex}{$\circledast$}}}}
\[
a \itsep^f_{g} b \qquad a \itsep^f_{g \, a \, b} b \qquad a \itsep^f_{\mathclap{g \, a \, b}} b
\]
\end{document}​

It depends on your use case whether this would be a problem when having excessively long subscripts, which may extend into the horizontal domain of the "operands" a and b.

Werner
  • 603,163
  • I've used \mathclap before and it certainly is an interesting solution to this problem (that I hadn't thought of), but it is my preference to simply make the symbol behave like other "big" symbols and only have to present a fix at the definition rather than fixing it at each instance as this mathclap solution does. – Arlen Cox Aug 02 '12 at 22:01