math-modesymbols
I'm trying to create a symbol \diffeo for "diffeomorphic" and \isomet for "isometric".
I'd like it to look exactly like \approx $\approx$, but with three lines for the first one; and three lines with the middle being straight for the second one:
where approx is the symbol
.
You can use the alignat environment from the amsmath package.
\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{alignat}{6}
X&={}& A&AA &{}+{}& B&B&B &{}+{}& C&C&C \\
&={}& &a &{}+{}& &b& &{}+{}& &c&
\end{alignat}
Basically you have to just do it by eye, as you have done. TeX has no information about the line widths (or the shape of the glyph at all). Even if you look in to the type1 or metafont sources of the font and find out the original design widths, you can not ensure at small sizes that you get exactly the same width using a rule, as the lines in the font are subject to the renderer's font hinting mechanism which may snap the lines on to pixel boundaries, whereas rules are drawn by different mechanisms and not subject to the same hinting.
You might do better just offsetting the same character so the rules are subject to the same hinting:
\documentclass{article}
\usepackage{graphicx}
\newcommand{\sqqcup}{\,{{\sqcup}\hspace*{-0.6em}\raisebox{-0.25ex}{--}}\;}
\def\xsqqcupb#1#2{\mathbin{\rlap{\raisebox{.15em}{$#1#2$}}{#2}}}
\def\sqqcupb{\mathpalette\xsqqcupb\sqcup}
\begin{document}
\[
\scalebox{8}{$a \sqqcup b$}
\]
\[
\scalebox{8}{$a \sqqcupb b$}
\]
\end{document}
Update:
As discussed in the comments it would be possible to hide the extra height with a coloured rule, but beware that the colour may hide more than you intend 9note the top bar of the fbox in the modified example)
\documentclass{article}
\usepackage{graphicx,color}
\newcommand{\sqqcup}{\,{{\sqcup}\hspace*{-0.6em}\raisebox{-0.25ex}{--}}\;}
\def\xsqqcupb#1#2{\rlap{\raisebox{.15em}{$#1#2$}}{#2}}
\def\sqqcupb{\mathbin{\mathpalette\xsqqcupb\sqcup}}
\def\xsqqcupc#1#2{\smash{\rlap{\raisebox{.15em}{$#1#2$}}\rlap{\color{white}\rule[.3em]{0.7em}{1.1ex}}}{#2}}
\def\sqqcupc{\mathbin{\mathpalette\xsqqcupc\sqcup}}
\begin{document}
\fbox{\scalebox{8}{$a \sqqcup x$}}
\bigskip
\fbox{\scalebox{8}{$a \sqqcupb x$}}
\bigskip
\fbox{\scalebox{8}{$a \sqqcupc x$}}
\end{document}
Best Answer
The first of the following macros is in the Comprehensive List of LaTeX Symbols (
texdoc symbols, with TeX Live), where it is called\threesim; the second one has been built similarly.