symbols
Possible Duplicate:
How to look up a math symbol?
I just could not find the command to write the symbol in Baby Rudin (Principles of Mathematical Analysis) for the set of bounded continuous functions on metric space X, for example on page 150 of its 1976 edition.
Whilst I wouldn't go so far as to define completely new symbols, I do occasionally find myself wanting slightly different ones than the standard set. Where I've encountered this is with arrows when lecturing: I find that I want the ⇔ to look a little more important, for example. For those cases, I redraw it using TikZ:
\newcommand{\textIff}{\tikz \draw (-3ex,.25ex) -- (-.25ex,.25ex) (-3ex,-.25ex) -- (-.25ex,-.25ex) (-.5ex,.5ex) -- (0,0) -- (-.5ex,-.5ex) (-2.75ex,.5ex) -- (-3.25ex,0) -- (-2.75ex,-.5ex);\xspace}
\newcommand{\mathIff}{\mathrel{\textIff}}
\newcommand{\Iff}{\ifmmode\mathIff\else\textIff\fi\xspace}
I guess that using TikZ rather than MetaFont for this is that I already know how to use TikZ for my other diagrams.
You can build the symbols yourself.
\documentclass{article}
\usepackage{pict2e}
\makeatletter
\DeclareRobustCommand{\loplus}{\mathbin{\mathpalette\dog@lsemi{+}}}
\DeclareRobustCommand{\lotimes}{\mathbin{\mathpalette\dog@lsemi{\times}}}
\DeclareRobustCommand{\roplus}{\mathbin{\mathpalette\dog@rsemi{+}}}
\DeclareRobustCommand{\rotimes}{\mathbin{\mathpalette\dog@rsemi{\times}}}
\newcommand{\dog@rsemi}[2]{\dog@semi{#1}{#2}{-90,90}}
\newcommand{\dog@lsemi}[2]{\dog@semi{#1}{#2}{270,90}}
\newcommand{\dog@semi}[3]{%
\begingroup
\sbox\z@{$\m@th#1#2$}%
\setlength{\unitlength}{\dimexpr\ht\z@+\dp\z@\relax}%
\makebox[\wd\z@]{\raisebox{-\dp\z@}{%
\begin{picture}(1,1)
\linethickness{\variable@rule{#1}}
\roundcap
\put(0.5,0.5){\makebox(0,0){\raisebox{\dp\z@}{$\m@th#1#2$}}}
\put(0.5,0.5){\arc[#3]{0.5}}
\end{picture}%
}}%
\endgroup
}
\newcommand{\variable@rule}[1]{%
\fontdimen8
\ifx#1\displaystyle\textfont3\else
\ifx#1\textstyle\textfont3\else
\ifx#1\scriptstyle\scriptfont3\else
\scriptscriptfont3\relax
\fi\fi\fi
}
\makeatother
\begin{document}
$A\roplus B\rotimes C\loplus D \lotimes E$
$\scriptstyle \roplus\rotimes\loplus\lotimes$
\end{document}
However, note that the standard \oplus and \otimes are lighter than + and \times, so you may want to redefine also them in a similar way, using the full circle.
Best Answer
You mean the curly C? I think you want