How to put a symbol above another

Following this question, I'm having problems when using the accepted answer on subscripts.

$A_ {z {_{y}^{x}} {_{x}^{y}} } \qquad {z {_{y}^{x}} {_{x}^{y}} }$


I don't know why, when in a subscript, the alignement/centering messes up.

I've also tried other options. I'll comment them a bit.

• \atop , \genfrac and \above
$A_ {z {x \atop y} {y \atop x} } \qquad {z {x \atop y} {y \atop x} }$
$A_ {z {\genfrac{}{}{0pt}{2}{x}{y}} {\genfrac{}{}{0pt}{2}{y}{x}} } \qquad {z {\genfrac{}{}{0pt}{2}{x}{y}} {\genfrac{}{}{0pt}{2}{y}{x}} }$
$A_ {z {x \above 0pt y} {y \above 0pt x} } \qquad {z {x \above 0pt y} {y \above 0pt x} }$


They seem to render exactly the same. They have too much blank space.

• \stackanchor from "stackengine" package
\stackMath
$A_ {z {\stackanchor{x}{y}} {\stackanchor{y}{x}} } \qquad {z {\stackanchor{x}{y}} {\stackanchor{y}{x}} }$


In both cases, it's misaligned. In the subscript, it's not the right size,

• \overset from "mathtools" package and \stackrel
$A_ {z {\overset{x}{y}} {\overset{y}{x}} } \qquad {z {\overset{x}{y}} {\overset{y}{x}} }$
$A_ {z {\stackrel{x}{y}} {\stackrel{y}{x}} } \qquad {z {\stackrel{x}{y}} {\stackrel{y}{x}} }$


They seem to render exactly the same. In both cases, not centered, neither the correct size.

By "aligned" I mean "$xy$ alignment", so "misaligned" refers to anything else. There's no need that it renders strictly perfect aligned, centered or sized: something close will do.

Desired output:

• do you want something like this? [ A_{z_{y^{x}}^{x^{y}}} \qquad z_{y^{x}}^{x^{y}} ] Sep 24 '21 at 1:01
• @EdsonMarcon, thanks, but no. I added an image to clarify. Sep 24 '21 at 3:52

Do you want to stack the objects? In this case a version of \atop can do it (using \genfrac, of course). The trick is to force \textstyle when the object is found in \displaystyle, otherwise the standard action is good.

\documentclass{article}
\usepackage{amsmath}

\makeatletter
\newcommand{\stk}[2]{\mathinner{\!\mathpalette\stk@{{#1}{#2}}\!}}
\newcommand{\stk@}[2]{%
\ifx#1\displaystyle
\expandafter\@firstoftwo
\else
\expandafter\@secondoftwo
\fi
{\genfrac{}{}{0pt}{1}}%
{\genfrac{}{}{0pt}{}}%
#2%
}
\makeatother

\begin{document}

$A_{z\stk{x}{y}\stk{y}{x}} \qquad z\stk{x}{y}\stk{y}{x}\ne z_{xy}^{yx} \qquad z\stk{aa}{b}\stk{b}{aa}$

\end{document}


• Thank you for your answer. This will do. Sep 24 '21 at 16:18

Something like this? (Observe: no need for \overset, \stackanchor, \atop, etc.)

\documentclass{article}
\newcommand\complicatedz{z_{yx}^{xy}}
\begin{document}
$\complicatedz \quad A_{\complicatedz} \quad A_{\complicatedz}^{}$
\end{document}


The two A_{...} terms differ, very slightly, in the vertical positioning of the subscript term -- which I've called, not very imaginatively, \zcomplicated.

• Thanks for your answer! I can't believe I haven't thought of such simple approach. It renders perfectly for this cases. However, I apologize for not being clear enough on my purposes: both _x^y and _y^x are different objects. Therefore, I could use something like egreg's third example or having a z in between the x, y. Sep 24 '21 at 16:16