# How to create horizontally aligned subscripts in latex

My problem is that I can't align subscripts properly.

I want subscript 'ISI' to be at same level for both H and x. while (m,n) remains in italic format. The last expression gives aligned subscripts but then the superscript is shifted that is not what I am looking for.

in isolation I want

\mathrm{x}^{(m,n)}_{ISI}


Also can anyone suggest a way to bold H and x.

I have tried the following, but nothing fixes my problem.

y(m,n)  =\mathrm{H}_{ISI}  \mathrm{x}^{(m,n)}_{ISI} + w(m,n)
\\
y(m,n)=\mathrm{H_{ISI} x_{ISI}^{(m,n)}} + w(m,n)
\\
y(m,n)=\mathrm{H_{ISI} x_{ISI}}^{(m,n)} + w(m,n)

• Welcome to TeX.SX! Your post was migrated here from Stack Overflow. Please register on this site, too, and make sure that both accounts are associated with each other (by using the same OpenID), otherwise you won't be able to comment on or accept answers or edit your question. Sep 14, 2014 at 23:33
• This is very similar to tex.stackexchange.com/q/3223/15925 . Do the solutions there help? Sep 15, 2014 at 7:08

If the exponent to x had “normal size”, for instance if it is just mn, an empty superscript to H would suffice as the second example shows. In the present case the parentheses force more lowering of the subscript, which can be obtained with \mathstrut also for H.

TeX places subscripts and superscripts considering only the base symbol, it doesn't know what comes along, so it needs help in these situations.

\documentclass{article}
\begin{document}
$y(m,n)=\mathrm{H}^{\mathstrut}_{ISI}\mathrm{x}^{(m,n)}_{ISI} + w(m,n)$

$y(m,n)=\mathrm{H}^{}_{ISI}\mathrm{x}^{mn}_{ISI} + w(m,n)$
\end{document}


\documentclass{book}
\usepackage{amsmath}

\begin{document}
$y(m,n) =\mathbf{H}^{\vphantom{(m,n)}}_{ISI} \mathbf{x}^{(m,n)}_{ISI} + w(m,n)$
\end{document}