[Tex/LaTex] Typesetting a function restriction with a bar shorter than \big

math-mode

The question about function restrictions didn't solve my problem, nor did the related questions about bigger parenthesis larger than Bigg.

I'd like to typeset a function restriction, with the vertical bar a bit lowered. f_{\big|W} results in something close to what I want:

To perfect it, the bar would be cut off where it reaches the baseline of the subscript symbol (in this case W). So that it doesn't reach below it.

How can I accomplish that?

Best Answer

\vrule inside an horizontal box has the property to match the height and depth of this box. Also all dimensions (height, depth, width) can be explicitly specified.

Example:

\documentclass{article}
\begin{document}
\[ f_{\mkern 1mu \vrule height 2ex\mkern2mu W} \]
\end{document}

The spacing around the vertical bar is achieved by \mkern to use the math unit mu that adopts to the current math style automatically.
The "W" looks a tiny bit lower than the rule. The reason is that "W" draws this tiny bit outside its character bounding box. The depth can be explicitly specified for fine-tuning.

Related Solutions

[Tex/LaTex] One more question regarding “function restriction”

You can say (requires amssymb, of course)

\renewcommand{\restriction}{\mathord{\upharpoonright}}

and the result will be as in the second line in the following picture, while the first line represents what you get now

enter image description here

[Tex/LaTex] Typesetting Meijer’s G function in LaTeX

One possibility: I used \DeclarePairedDelimiterX from the mathtools package to define a \MeijerM command with three arguments which is responsible to typeset the delimited matrix; then I defined \MeijerG having eight arguments (the first one is optional and will be passed as the optional argument to \MeijerM); using the \WithSuffix command from the suffix package to provide the starred version \MeijerG*:

\documentclass[11pt]{article}
\usepackage{suffix}
\usepackage{mathtools}

\DeclarePairedDelimiterX\MeijerM[3]{\lparen}{\rparen}%
{\begin{smallmatrix}#1 \\ #2\end{smallmatrix}\delimsize\vert\,#3}

\newcommand\MeijerG[8][]{%
  G^{\,#2,#3}_{#4,#5}\MeijerM[#1]{#6}{#7}{#8}}

\WithSuffix\newcommand\MeijerG*[7]{%
  G^{\,#1,#2}_{#3,#4}\MeijerM*{#5}{#6}{#7}}

\begin{document}

\[
\MeijerG*{m}{n}{p}{q}{a_1, \dots, a_p}{b_1, \dots, b_q}{z}\quad
\MeijerG[\big]{m}{n}{p}{q}{a_1, \dots, a_p}{b_1, \dots, b_q}{z}\quad
\MeijerG[\Bigg]{m}{n}{p}{q}{a_1, \dots, a_p}{b_1, \dots, b_q}{z}
\]

\end{document}

enter image description here

The size of delimiters in the second and third examples is obviously wrong, but I just included them to test the functionality of the defined commands. Also, I used simple sub/superscripts to typeset the first four arguments, but of course you can use one of your proposed variants instead.