plot issues

[Ethan Merritt]

On Friday 05 June 2009, Ben Abbott wrote:
> 

> >>
> >> Petr, what are the benefits of the pdfcairo and pngcairo terminals  
> >> over the pdf and png terminals?

Aside from licensing issues for PDFLib, using cairo to generate the plots
allows antialiasing, transparency, and UTF-8 support.  

> Are there any license problems with the plain png terminal, or is it  
> just the pdf?

The "plain png" terminal has not been supported for about 8 years now.
Instead the default is to use libgd, and the newer option is to use
cairo.  None of these has any licensing issues that I am aware of.
 
> Presently, when the pdf terminal is specified, the print() function  
> checks with gnuplot to determine if the "pdf" terminal is supported.  
> If not, or unknown, print() checks for the presence of ghostscript. If  
> present, the ps terminal is used to produce a ps-file and then  
> ghostscript is used to convert to pdf.

Going through an intermediate postscript file is non-optimal, because
PostScript itself does not support transparency or UTF-8 characters.
At least from the perspective of plot quality, this is probably the
least satisfactory of several options.
It would be better to use either pdfcairo or the brand new tikz terminal.

Does Octave have a confguration file or configuration menu that the
user can find easily?  I suggest to make the production of pdf output a
user-configurable choice.  
PDF output via (select one)
   -->  pdf (let gnuplot choose for you)
   -->  pdfcairo
   -->  tikz / pdflatex
   -->  PostScript / ps2pdf