[Kst] muparser / kst plugin for nonlineary curve fitting

[Brisset, Nicolas]

> Hi Nicolas,
> 
> I'm the author of muParser. While searching google I found 
> out that you wrote a plugin for kst that uses muParser. I 
> would like to try it out but could not find a link to the 
> latest (nonstable) versions. Can you please give me a 
> download link or mail me the archive? I'm always interested 
> to see in what kind of projects the library is beeing used.
Sure. Kst is currently only in the KDE svn module named
extragear/graphics, which you can download via the following command:
"svn svn co svn://anonsvn.kde.org/home/kde/trunk/extragear/graphics".
You will need a KDE installation, not necessarily bleeding edge though
for kst (so if you're running Linux, you can probably compile it with
your current distribution and the standard KDE packages). Once you've
downloaded the files, you have to cd into the graphics/ directory, and
issue the "make -f Makefile.cvs command", then it is the standard
"./configure [options] ; make && make install" process. 
You will also benefit from libgsl-devel for other fit and filter plugins
but it's not a requirement. Kst is a cool and very actively developed
plotting tool, much faster than qtiplot albeit it currently provides
less plot types. The plugin has been committed to svn only a few days
ago, and is currently disabled from compilation. You have to build it
yourself using the provided Makefile, then you can pick it up with the
plugin manager by cliking on the associated .xml (I can provide more
detailed instructions if you need, but I'd suggest you first get and
build kst...). It works well with the example provided (3rd order
polynomial, but I have problems with an expression of the form
y=a*exp(-bx)+c, which seems to crash or converge poorly when it doesn't.
I have not had time to investigate it further though, but if you want to
look at it I don't mind :-)

> I will add a link to kst on the muParser homepage. If the kst 
> homepage has a related links section I would appreciate a 
> backlink to the muParser homepage in case the plugin becomes 
> part of the standard kst package. This is of course not a 
> requirement in order to use it but it is something that may 
> help me if I need to use muParser as a reference project for 
> my next job application.
I understand that. I will cc: this mail to the kst mailing-list so that
the appropriate people can decide on references to include. Currently,
the usage of the muparser is very limited and I have no idea whether it
will change, as kst has its own parser. My plugin being a very recent
addition at a time when the next stable version (1.2.0) is trying to be
stabilized, this really has not been discussed yet.

> If you have questions or suggestions on the usage of the 
> parser feel free to ask me.
It seems to be a nice parser from what I can tell. Apart from the
problem mentioned above, which may be well be a bug on my side, the only
comment I have so far is that the syntax has changed a lot since the
version qtiplot uses :-) Fortunately, your web page provides sufficient
information and the example that helped me make it work. 

Feel free to try out kst and comment on it (it has a bugzilla for
bugs/feature requests and a very active community of developers). I find
it excellent and I believe it will still improve a lot in the future.

Nicolas