On Wed, 26 Sep 2007, Talha Yalta wrote:
 Thanks Allin. I want to report this to gnuplot developers but I 
 wonder why it is possible to save the graphs correctly when 
 exporting as png. Is this a different thing? 
Yes.  Gnuplot includes a large set of drivers or "terminals" for 
different plot formats.  They are trying to standardize these so 
far as possible, but they are still far from identical.  And in 
fact they can't all be identical, because the inherent 
feature-sets differ to some degree across the various target 
formats.
In this case, the key difference is that the PNG formatter accepts 
utf-8 text while the PostScript one does not.
My thought was to convert the text encoding from utf-8 to latin-9 
before passing the information to gnuplot, but that doesn't help, 
since gnuplot doesn't support latin-9 encoding.  Presumably that 
could be fixed without too much difficulty, within gnuplot.  I'll 
take a look at that issue.
 Also I noticed gnuplot is not distirbuted under the GPL and it 
 is not free software since the license doesn't let distributing 
 modified versions of the program.  
No, it's not GPL'd, but you can distribute modified versions.  
The license is a bit quirky.  "Modifications are to be distributed 
as patches to the released version."
 Is gnuplot the only alternative for the plotter application in 
 gretl? Is it possible to, say, using the plotting engine of R or 
 qtiplot which I believe are distributed under the GPL.  
qtiplot would drag in the Qt libraries as a dependency for gretl, 
and I don't want to do that.  Although gnuplot has some problems, 
I still favour it because
* It is so flexible: you can save the plot commands and do all 
sorts of things with them, with the help of the gnuplot manual.
* It's under active development, is being improved all the time, 
and is probably the closest thing to a "standard" for scientific 
plotting in the open-source world.
Allin.