# Fixing the vertical position of subscripts

When I write $\chi_V$ the subscript outputs too high for my taste. Is there a way I can set the vertical position of subscripts for the whole document?

Many thanks

• A general solution: Redefine the default depth of superscript and subscript document-wide
– Werner
Apr 9 '15 at 21:46
• Do you ever have \chi with a superscript? If not, then you could do \let\oldchi\chi\renewcommand{\chi}{\oldchi^{}}; this inserts a blank superscript, shifting the subscript down slightly which might suit you better.
– Werner
Apr 9 '15 at 21:55
• I do use subscripts yes. I can't seem to get the other solution to work either (I am not very good at this). More help? I get the error "nullfont has only 7 fontdimen parameters" Apr 9 '15 at 21:56
• I asked about superscripts, not subscripts. Do you use superscripts with \chi?
– Werner
Apr 9 '15 at 22:25
• sorry - I meant to write superscripts :) Apr 9 '15 at 22:33

I interpret the objective of your posting as wishing to modify (specifically, increase) the math subscript offset for all subscripts in the entire document.

If this interpretation is correct, the following LuaLaTeX-based solution may be of interest to you. It works by modifying the "primitive" length parameter \Umathsubshiftdown. For a document set in 10pt ("10 point") font size, the default value of this parameter is 1.5pt; in the example below, I suggest using a value of 2.5pt.

% !TEX TS-program = lualatex
\documentclass{article}
\begin{document}
$\chi_V \ a_i$ --- default

% change the parameter "\Umathsubshiftdown"
\Umathsubshiftdown\textstyle=2.5pt
\Umathsubshiftdown\displaystyle=2.5pt

$\chi_V \ a_i$ --- modified \texttt{\textbackslash Umathsubshiftdown}

\end{document}