[Xy-pic] Tip sizes when using the slides class

[Michael Abbott]

> To get a good result with slides, you need to do either:
>
>   1.  use the PostScript extensions, with a suitable driver;
>      e.g.  \usepackage[ps,dvips,rotate,frame,all]{xy}
>      and  \UsePSspecials   (if necessary)
>      and \UsePSframes, etc.

Well, I've tried:

\documentclass{slides}
\usepackage[ps,dvips,all]{xy}
\SelectTips{cm}{}   % To compare like with like below
\begin{document}
\begin{slide}
Compare $\xymatrix{A \ar[r] & B}$ with $A\rightarrow B$.
\end{slide}
\end{document}

and it makes no difference; the arrowhead is still far too small.

The only effect of adding \UsePSspecials{dvips} seems to be the message:
	Xy-pic Warning: PostScript switched off [test:7].

Finally, I can find no documentation for the \UsePSframes command (in
particular, it's not in the index for my "Xy-pic Reference Manual").
I've tried dropping it in various places, where it has had no visibile
effect.

>      You will need a PostScript based viewer to see the results.
>
> OR
>   2.  layout your slides on a paper-size reduced sufficiently
>       to look good with 10pt fonts; e.g.  B7 or A6 size.
>       Then view the results magnified to fill the window/screen.

Umm.  This is a whole new can of worms, in particular I'll need to create
a whole new style for this.  I can't believe that no-one has solve the
problem of creating slides for presentations with XyPic.

>      This is the best with pdfTeX/pdfLaTeX, which is currently not
>      compatible with Xy-pic's PostScript extensions.

Well, unfortunately I *will* need to use the PostScript extensions, as
XyPic's drawing of circles is somewhat inaccurate otherwise.

> Hope this helps,

Well, I'm glad of your response, but: can I ask you to be a little more
explicit, please?  For example, can you modify my eight lines of TeX to
work?

> 	Ross Moore