[Xy-pic] Difference between dvi and pdf output

[Ross Moore]

Hi Michael,

On 18/09/2012, at 3:36 AM, Michael Barr wrote:

> Can anyone explain the difference in ouput between this file:
> 
> \documentclass{article}
> \pdfoutput1
> \usepackage{xy}

> and this one:
> 
> 
> \documentclass{article}
> \pdfoutput0
> \usepackage{xy}
> 
> \begin{document}
> 
> \begin{xy}
> 0;<1cm,0cm>:
> (8,3) *\cir<2cm>{},
> (8.3,2.7) *\cir<1.4cm>{},
> (6.4,3.1) *\cir<0.2cm>{}
> \end{xy}
> 
> \end{document}
> 
> They differ only in the output chosen.  The first gives pdf and the
> second dvi.

If you use just \pdfoutput to generate the .dvi version,
then you are limited to the finite number of circle sizes
that are encoded into the  xycirc10  font.
There is a maximum size for the radius that is less than 2cm.

With PDF output, since the  xypdf.sty  package has become
available, you can get arbitrary radius lengths.

If you need to go the  .dvi --> .ps --> .pdf  route,
then you should be loading Xy-pic as follows:

 \usepackage[ps,dvips,all,...]{xy} 

(or with   \xyoption{ps}\xyoption{dvips} )

with ... allowing extra optional features to be specified.
This causes the drawing to be done use PostScript \special commands,
rather than placing font characters.
 --- check the fonts that make it into the resulting PDF.

Using the PostScript back-end this way has been available since
Xy-pic v3, written in the 1990s.
(i.e., since before PDF was invented!)


> 
> Incidentally, the second output is duplicated if the \usepackage{xy}
> precedes the line \pdfoutput1, which I find doubly bizarre.
> 
> 
> Michael Barr



Hope this helps,

	Ross

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Ross Moore                                       ross.moore at mq.edu.au 
Mathematics Department                           office: E7A-419      
Macquarie University                             tel: +61 (0)2 9850 8955
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