In Rudin's Real and Complex Analysis, there is a symbol for stating measure $\lambda$ is absolutely continuous with respect to measure $\mu$. The symbol is like $\lambda\ll\mu$, but not exactly.
[Tex/LaTex] How to write Rudin’s symbol for absolute continuity of measures
math-modesymbols
Related Solutions
The example defines \eexists and \fforall with the additional lines as requested in the question.
\eexists: The symbol\eexistsis composed of\existsand the vertical line|to get a line with a matching line thickness. The vertical line is scaled to the right height. This vertical scaling does not change the horizontal line width. Finally the line is moved to the right position.\fforall: The trick with the vertical line cannot be uses, because the angle is not known exactly. Also the angle depends on the font size. The angle can be estimated from the width and height of the symbol. For this symbolTikZis used and the line width is guessed from the width of\forall.
Update:
- Decreased distance between the two lines.
- I have removed the case for
\scriptscriptstyle, because the symbols have larger side bearings that would need to be compensated. But probably the symbols are not needed at such sizes anyway. - Of course, the "magic numbers" depend on the used font. A different font might need different settings.
Example file:
\documentclass{article}
\usepackage{graphicx}
\usepackage{tikz}
\makeatletter
\newcommand*{\eexists}{%
{\mathpalette\eexistsAux{}}%
}
\newcommand*{\eexistsAux}[2]{%
\exists
\sbox0{$\m@th#1\exists$}%
\sbox2{\raisebox{\depth}{$\m@th#1|$}}%
\kern-.5\wd2 %
\resizebox{\width}{\ht0}{\copy2}%
\kern-.25\wd2 %
}
\newcommand*{\fforall}{%
{\mathpalette\fforallAux{}}%
}
\newcommand*{\fforallAuxx}[1]{%
\sbox0{$\m@th#1\forall$}%
\sbox2{%
\rlap{%
\raisebox{\depth}{$\m@th#1\backslash$}%
}%
\kern\ht0 %
}%
\sbox2{\resizebox{\ht2}{\height}{\copy2}}%
\sbox2{\resizebox{!}{\ht0}{\copy2}}%
\wd2=0pt %
\copy2
\forall
}
\newsavebox\forallBox
\newdimen\forallLineWidth
\newdimen\forallSep
\newcommand*{\fforallAux}[1]{%
\sbox\forallBox{$\m@th#1\forall$}%
\setlength{\forallLineWidth}{.06\wd\forallBox}%
\setlength{\forallSep}{.09\wd\forallBox}%
\tikz[
inner sep=0pt,
line cap=round,
line width=\forallLineWidth,
]
\draw
(0,0) node (A) {\copy\forallBox}
(A.south) ++(-\forallSep-\forallLineWidth,.4\forallLineWidth)
coordinate (A1)
(A.north west) ++(-\forallSep,-\forallLineWidth)
coordinate (A2)
(A1) -- (A2)
;%
}
\makeatother
\begin{document}
\setlength{\fboxsep}{0pt}
\renewcommand*{\arraystretch}{1.5}
\begin{tabular}{cc}
\fbox{$\forall$} & \fbox{$\exists$}\\
\fbox{$\fforall$} & \fbox{$\eexists$}\\
$\forall^\forall$ & $\exists^\exists$ \\
$\fforall^\fforall$ & $\eexists^\eexists$\\
\end{tabular}
\end{document}
Package colonequals provides a vertically centered colon: \ratio. Both \ratio and \Leftrightarrow are of kind \mathrel, therefore TeX will not put additional space between them:
\documentclass{article}
\usepackage{colonequals}
\newcommand*{\logeq}{\ratio\Leftrightarrow}
\begin{document}
\[ A \logeq B \]
\end{document}
When additional space is wanted between the colon and the arrow (see Raphaels's comment), then \colonsep can be defined and set between the symbols, e.g.:
\renewcommand*{\colonsep}{\mkern1mu\relax}% small extra space
\newcommand*{\logeq}{%
\mathrel{\ratio\colonsep\Leftrightarrow}%
}
P.S.
It does not matter here, whether the star form of \newcommand is used or not, because there aren't any argument and the definition is not empty. Therefore it is mostly a matter of taste here.
I prefer the star form, because I am thinking rather in terms of lower level commands. \newcommand* uses \def, whereas \newcommand uses \long\def. Without arguments I do not see a reason for \long, therefore I am using \newcommand*.
Best Answer
If one doesn't want to load the whole lot of mathabx, that changes the shape of many symbols, it's possible to load only the one needed, see Importing a single symbol font from a different font.
The definition would be
using the unicode-math name or, if the alternative way by pisymbol is preferred,
The complete series of declarations in the preamble should be
If your TeX distribution is fairly recent you can leave out the commented lines (starting with
%); otherwise, uncomment them and delete the similar ones above. It has to do with the presence of the Type1 (scalable) versions of the mathabx fonts.With the alternative method that doesn't reserve a math alphabet, the code to write in the preamble is
For the
\DeclareFontShapecommand it's the same as before.