subscriptssuperscripts
I have a variable with a subscript describer P_{\rm 1S} I'd like to square it.
First a style question: is (P_{\rm 1S})^2 or P_{\rm 1S}^2 better? The programming part of the problem is that the latter aligns the superscript vertically above the subscript, I would like the power to be aligned further to the right distinct from the variable and its descriptors. Is there a simple way to do this?
It's not clear exactly what layout you want, (perhaps a full minimal example and image in your question would have helped).
The main function of \operatorname is to provide multi-letter operators like log etc, if you want a math italic f it seems that you just need one of these, depending on where you want the limits to go.
The other function is to give it operator spacing, ie a small gap before the argument, so perhaps the first or second form is what you are looking for?
$ f_1^2 x $
$ \mathop{f_1^2} x $
$ \mathop{{}f}_1^2 x $
$ \mathop{{}f}\limits_1^2 x $
This should work exactly as desired:
\documentclass[a4paper]{article}
\usepackage{amssymb,amsmath}
\pagestyle{empty}
\makeatletter
\newcommand*\jjoin{\@ifnextchar_\jj@in\jj@@n}
\newcommand*\jj@@n{\bigvee\nolimits^{(J)}}
\newcommand*\jj@in[2]{\mathchoice
{\mathop{\jj@@n}_{#2\phantom{(J)}}}%
{\jj@@n_{#2}}%
{\jj@@n_{#2}}%
{\jj@@n_{#2}}%
}
\makeatother
\begin{document}
Inline: $A=\jjoin B \qquad A=\jjoin_{i\in I} B_i$
Display: \[A=\jjoin B \qquad A=\jjoin_{i\in I} B_i\]
\end{document}
Best Answer
Instead of
$(P_{\rm 1S})^2$(which is the most precise) you can also write${P_{\rm 1S}}^2$(which should be also clear). However, as it is mentioned by egreg,P_\mathrm{1S}is better thanP_{\rm 1S}, as\rmis obsolete in LaTeX2epsilon.