Math-Mode Symbols Overlays – Overlay a 0 with a |

math-modeoverlayssymbols

How can I overlay a 0 with a | in latex to create a new symbol comprised of a 0 with a vertical line inside it?

I've looked at the following post Overlay symbol with another and tried to adapt the code provided in one of the answers, because I didn't understood the accepted answer, but this did not output the symbol that I wanted.

\newcommand\cz{\mathrel{\ooalign{$|$\cr\hidewidth$0$\hidewidth\cr}}}

The vertical dash would go out of the zero and when I wrote another letter next to this symbol the spacing would be incorrect. In order to try and understand the accepted answer I tried to look for the commands used there, like \rlap, \setbox, …, in the web and in the latex reference provided with texmaker under the help tab but the web pages I found explainde very poorly these commands and the latex refence didn't even had them. Where can I find the official documentation for these commands or any other good resource to learn them?

Best Answer

Made to work in all math styles. I overlay a stretched \vert inside a 0.

\documentclass{article}
\usepackage{stackengine,scalerel}
\newcommand\vertzero{\ThisStyle{\ensurestackMath{\stackengine
  {0pt}{\SavedStyle0}{\SavedStyle\stretchrel*{\vert}{0}}%
  {O}{c}{F}{F}{L}}}}
\begin{document}
$\vertzero\scriptstyle\vertzero\scriptscriptstyle\vertzero$
\end{document}

If one did not like seeing, under high magnification, the rounded extrema of the \vert, one could tweak it as

\documentclass{article}
\usepackage{stackengine,scalerel}
\newcommand\vertzero{\ThisStyle{\ensurestackMath{\stackengine
  {0pt}{\SavedStyle0}%
  {\SavedStyle\stretchrel*{\vert}{\addstackgap[.1\LMpt]{\SavedStyle0}}}%
  {O}{c}{F}{F}{L}}}}
\begin{document}
$\vertzero\scriptstyle\vertzero\scriptscriptstyle\vertzero$
\end{document}

If one wanted more control over the width of the bar, replacing the \vert with a \rule of specified width would provide that flexibility. Here, I make the width .6\LMpt, where \LMpt is a measure of pt that is scaled in the smaller math styles.

\documentclass{article}
\usepackage{stackengine,scalerel}
\newcommand\vertzero{\ThisStyle{\ensurestackMath{\stackengine
  {0pt}{\SavedStyle0}{\SavedStyle\stretchrel*{\rule{.6\LMpt}{1ex}}{0}}%
  {O}{c}{F}{F}{L}}}}
\begin{document}
$\vertzero\scriptstyle\vertzero\scriptscriptstyle\vertzero$
\end{document}

Result

Symbols – How to Create Dashed Right Arrow Over Symbol

OK, this is far from being perfect, but in some sense there is no perfectness on the route my answer you linked to. The problem is this: when we use the dashed arrow from MnSymbol as the arrow tip of an extensible dashed arrow, this symbol defines the length of the dash as well as the gap between dashes. If you also want the extensible dashed arrow to have exactly the same length as one of the standard extensible arrows like \overrightarrow, we have to compromise somewhere as not always an integral multiple of the (fixed) dashed pattern will match. So we will have uneven spaces somewhere.

\documentclass{article}

\usepackage{graphicx}

\DeclareFontFamily{U}{MnSymbolA}{}
\DeclareSymbolFont{MnSyA}{U}{MnSymbolA}{m}{n}
\DeclareFontShape{U}{MnSymbolA}{m}{n}{
    <-6>  MnSymbolA5
   <6-7>  MnSymbolA6
   <7-8>  MnSymbolA7
   <8-9>  MnSymbolA8
   <9-10> MnSymbolA9
  <10-12> MnSymbolA10
  <12->   MnSymbolA12}{}
\DeclareMathSymbol{\dashedleftarrow}{\mathrel}{MnSyA}{98}
\DeclareMathSymbol{\dashedrightarrow}{\mathrel}{MnSyA}{96}

\def\Gg{{\mathbf{G}}}
\def\gc{{\mathbf{g}}}

\newcommand{\toright}[1]{\overrightarrow{#1}}
\newcommand{\toleft}[1]{\overleftarrow{#1}}

\newcommand{\torightleft}[1]{\toleft{\toright{#1}}}
\newcommand{\toprerightleft}[1]{\toleft{\topreright{#1}}}
\newcommand{\torightpreleft}[1]{\topreleft{\toright{#1}}}
\newcommand{\toprerightpreleft}[1]{\topreleft{\topreright{#1}}}

\newcommand{\toleftright}[1]{\toright{\toleft{#1}}}
\newcommand{\topreleftright}[1]{\toright{\topreleft{#1}}}
\newcommand{\toleftpreright}[1]{\topreright{\toleft{#1}}}
\newcommand{\topreleftpreright}[1]{\topreright{\topreleft{#1}}}

\makeatletter
\newcommand{\topreleft}[1]{%
  \vbox {\m@th\ialign{##\crcr
  \topreleftfill \crcr
  \noalign{\kern-\p@\nointerlineskip}
  $\hfil\displaystyle{#1}\hfil$\crcr}}}

\newcommand{\topreright}[1]{%
  \vbox {\m@th\ialign{##\crcr
  \toprerightfill \crcr
  \noalign{\kern-\p@\nointerlineskip}
  $\hfil\displaystyle{#1}\hfil$\crcr}}}

%% fill with (short) minus signs
\def\topreleftfill{%
  $\m@th%
  \dashedleftarrowtip%
  \mkern-1mu%
  \xleaders\hbox{$\mkern2mu\shortbar\mkern-1mu$}\hfill%
  \mkern1mu%
  \shortbar%
  \mkern0.5mu%
$}

\def\toprerightfill{%
  $\m@th%
  \mkern.5mu%
  \shortbar%
  \mkern-1mu%
  \xleaders\hbox{$\mkern2mu\shortbar\mkern-1mu$}\hfill%
  \mkern1mu%
  ‌\dashedrightarrowtip%
$}

%% put 4.0pt space above and 0.0pt below the tip
\def\dashedleftarrowtip{%
  \raisebox{\z@}[4.0pt][0.0pt]{$\mathord{\dashedleftarrow}$}}

\def\dashedrightarrowtip{%
  \raisebox{\z@}[4.0pt][0.0pt]{$\mathord{\dashedrightarrow}$}}

%% make the minus shorter to fit \dashedleftarrow
\def\shortbar{%
  \smash{\scalebox{0.4}[1.0]{$-$}}}
\makeatother

\begin{document}
Arrow over G should fit nicely into the brackets:
\[%
  \left[\toleft{\Gg}\right] = \left[ \topreleft{\Gg} \right]
  = \left[\toright{\Gg}\right] = \left[ \topreright{\Gg} \right].
\]

Dashed right arrow and left arrow should be of the same length and align:
\[%
  \toprerightleft{\gc} = \topreleftright{\gc} = \torightpreleft{\gc} = \toleftpreright{\gc} = \toprerightpreleft{\gc} = \topreleftpreright{\gc} = \torightleft{\gc} = \torightleft{[\gc]}
\]

Left and right arrow should align and have the same length:
\[%
  \toprerightpreleft{\gc} = \toprerightpreleft{\Gg}
\]

\bigskip

\[%
  \topreright{\topreleft{x}} \quad \topreright{\topreleft{ab}} \quad \topreright{\topreleft{abc}} \quad \topreright{\topreleft{abcd}} \quad \topreright{\topreleft{abcde}}
\]

\[%
  \topreleft{\topreright{x}} \quad \topreleft{\topreright{ab}} \quad \topreleft{\topreright{abc}} \quad \topreleft{\topreright{abcd}} \quad \topreleft{\topreright{abcde}}
\]
\end{document}

sample output

So there is still some perfectness to be desired. Since you wanted to know how to tweak the parameters, here is how it works. The vertical layout is determined by the arrow tips. The definition

\def\dashedleftarrowtip{%
  \raisebox{\z@}[4.0pt][0.0pt]{$\mathord{\dashedleftarrow}$}}

says that thre is no space (0.0pt) below the arrow tip, and 4.0pt above. That way you can position the arrows and determine their distance when they are stacked. This also influences the size of the \left[...\right] braces, as those encompass also the white space above the arrow.

The horizontal pattern is determined by

\def\topreleftfill{%
  $\m@th%
  \dashedleftarrowtip%
  \mkern-1mu%
  \xleaders\hbox{$\mkern2mu\shortbar\mkern-1mu$}\hfill%
  \mkern1mu%
  \shortbar%
  \mkern0.5mu%
$}

Here, \mkern1mu is a horizontal kerning space of length 1mu=1/18\quad. The \xleaders command fills as much space as possible (\hfill) with the pattern \hbox{$\mkern2mu\shortbar\mkern-1mu$}, where the remaining space that can not be filled with another box is evenly distributed before, after and in between the repeated boxes.

Best Answer

Related Solutions

Math Mode – How to Overlay Symbol with Another

Result

Symbols – How to Create Dashed Right Arrow Over Symbol

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