# Better extensible arrows

Using amsmath and extarrows packages, we have many extensible arrows. But these arrows look ugly, since some parts in an arrow are boldfaced.

Are there any better-looking extensible arrows?

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They are not really bold, just overlapping slightly which affects the anti-aliasing in low resolution. They should print OK. tikz or pstricks or xypick can all draw arrows instead of using repeated character segments, which may suit you better – David Carlisle Oct 7 '13 at 8:52
@DavidCarlisle The overlapping makes arrows look ugly when reading document in computer. Why overlapping is necessary in these extensible arrows? I notice that in xypic, long arrows look better than these. – Z.H. Oct 7 '13 at 9:03
@DavidCarlisle But how to use an arrow drawn by tikz or xypic as an operater inside a math formula? It seems not easy. – Z.H. Oct 7 '13 at 9:14

This is a substitute for \xrightarrow made with Xy-pic

\documentclass{article}
\usepackage[all,cmtip]{xy}

\newlength{\xywd}
\newcommand{\xyrightarrow}[2][]{%
\sbox{0}{$\scriptstyle#1$}%
\xywd=\wd0
\sbox{0}{$\scriptstyle#2$}%
\ifdim\wd0>\xywd0 \xywd=\wd0 \fi
\xymatrix@C\dimexpr\xywd+1em\relax{{}\ar[r]^{#2}_{#1}&{}}%
}

\begin{document}
$X \xyrightarrow[r_1-r_2]{r_2-r_1} Y$
$X \xyrightarrow[r_1-r_2+r_3]{r_2-r_1} Y$
$X \xyrightarrow{r_2-r_1} Y$
\end{document}


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