[Tex/LaTex] Subscript after \underline in math mode

subscriptsunderline

I would like to put a subscript after a character with multiple underlines in the math mode but ignoring the underlines. How can I do it?

Consider this picture:

I would like the subscript to have the vertical position of the element with respect to the character. Here is the code the produced the picture:

\documentclass[border=5mm]{standalone}
\usepackage{ulem,amsmath,bm}
\begin{document}
\(C_{\text{c}}, 
\underline{\bm{C}}_{\text{c}}, 
\underline{\underline{\bm{C}}}_{\text{c}}, 
\uuline{\bm{C}}_{\text{c}}\)
\end{document}

Edit: Would be superb if the underline was limited to the width of the character.

Best Answer

Thanks to this answer, the following satisfied my requirements, including additional:

\newcommand{\ubar}[1]{\mkern 1.5mu\underline{\mkern-1.5mu#1\mkern-1.5mu}\mkern 1.5mu}
\newcommand{\uubar}[1]{\ubar{\ubar{#1}}}

Related Solutions

Math Mode Subscripts – How to Use Textual Subscripts in Math Mode

What you have tried is the right way. You can simplify it slightly and play with other fonts:

$$ W_\textrm{total} = \sum_i W_i $$

To make it prettier I'd suggest to think about the use of variables and indices in your work. For example, you could reserve W (without index) for the total which is the sum of w_i (lowercase w). This way you can avoid long subscripts.

Math Mode Subscripts – Problem Formatting a Subscript in Math Mode

This will overlap with Mico's answer, but there are couple of extra points that I'd like to make.

Loading amsmath has the nice feature that text font changing commands may be used in mathematics and the text resizes appropriately in subscripts etc. The commands \textrm, \textit etc. may be used directly without having to invoke an additional \text command. Often these direct commands are to be preferred over \text, because the latter inherits the font characterisitics from the surounding text. My standard solution for such situation is to define a macro and use the \textnormal command to avoid this.

\documentclass{article}

\usepackage{amsmath,amsthm}

\newtheorem{theorem}{Theorem}

\newcommand{\FHWM}{\textnormal{FHWM}}

\begin{document}

\( B_\FHWM \) vs. \( B_{\text{FHWM}} \) and
\( X_{B_\FHWM} \) vs. \( X_{B_{\text{FHWM}}} \)

\begin{theorem}
 Preferring \( B_\FHWM \) to  \( B_{\text{FHWM}} \)
\end{theorem}

\textbf{\( B_\FHWM \) vs. \( B_{\text{FHWM}} \)}
\end{document}

Sample output

An alternative to \textnormal is \textup, which will produce upright inside italic and slanted text, but will turn bold inside bold text.

However, in your case you are putting the subscript on a small symbol \nu and the above looks too big. The small caps shape from \textsc is often designed to give the best spacing for such combinations and is a standard choice for acronyms. You need to remember to write \textsc{fwhm} instead of \textsc{FWHM} as the latter usually produces capitals of the same size as \textrm capitals. One thing to be aware of is that the standard fonts have no bold variant of \textsc, so I suggest you additionally use \textnormal to avoid surprises. Your request for a very small font is provided by the \tiny command. (My personal preference would be to omit that or to use a command from the relsize package.) Below is an example with \tiny included.

\documentclass{article}

\usepackage{amsmath,amsthm}

\newtheorem{theorem}{Theorem}

\newcommand{\FHWM}{\textnormal{\tiny \textsc{fhwm}}}

\begin{document}

\( \nu_\FHWM \) vs. \( \nu_{\textsc{fhwm}} \) vs. \( \nu_{\text{FHWM}} \) 
and
\( X_{\nu_\FHWM} \) vs. \( X_{\nu_{\textsc{fhwm}}} \) vs. \( X_{\nu_{\text{FHWM}}} \)

\begin{theorem}
 Preferring \( \nu_\FHWM \) to  \( \nu_{\text{FHWM}} \)
\end{theorem}

\textbf{\( \nu_\FHWM \) vs. \( \nu_{\textsc{fhwm}} \) vs. \( \nu_{\text{FHWM}} \)}
\end{document}

Sample with textsc and tiny

The bold cases in the above examples are there just to illustrate pitfalls. If you really intend to use this in such contexts, then you need to think about what fonts you wish to appear and build the commands appropriately.

Best Answer

Related Solutions

Math Mode Subscripts – How to Use Textual Subscripts in Math Mode

Math Mode Subscripts – Problem Formatting a Subscript in Math Mode

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