Difference in height of subscript [duplicate]

Question

This question already has an answer here:

• Subscripts for primed variables 4 answers

I have a problem concerning the following equation in LaTeX:

A_{1}^{\ast} A_{1} = A_{1} A_{1}^{\ast},

where the 1's under the A's are placed at different heights. Does anyone know a simple way to fix this?

Answer 1

It's the lack of a superscript that's creating the problem. Because of the size of the superscript, the subscript was pushed down. Use a phantom superscript to equalize things.

\documentclass{article}
\pagestyle{empty}
\begin{document}
\[
    A_{1}^{\ast} A_{1}^{\phantom{\ast}} = A_{1}^{\phantom{\ast}} A_{1}^{\ast}
\]
\end{document}