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Re: gEDA-user: On integrating simulator in gschem
Dan McMahill wrote:
>> IMHO, there are already very mature open source data plotters out there.
>> Think gnuplot, or grace. What is the rationale in rolling your own?
>
> unless I'm missing some key feature of gnuplot and grace, they stink for
> plotting simulator output.
I used grace quite a bit, both as an interactive GUI and integrated into the
data software of my physics experiment. So let's see:
> I spend a lot of time looking at simulator output and some of the
> things which are used over and over again are
> easy interactive zoom in/out,
[ctrl + ] for zoom, [ctrl - ] for unzoom.
> panning at a fixed zoom,
a) left mouse butten click'n drag in both directions
b) scrollwheel vertical, ctrl+scrollwheel horizontal
c) drag dedicated scrollbars
> putting cursors on waveforms that will lock onto the actual datapoints,
these are called "trackers" in xmgrace
> having delta cursors, and
> having a flexible and extensible waveform calculator.
see this page for a cursory list of functions:
http://plasma-gate.weizmann.ac.il/Xmgr/doc/trans.html
Note, the list of features that can be automatically extracted at the bottom
of the page.
> The types of
> postprocessing range from the very simple (out_plus - out-minus) to more
> complex but standard like an fft to fairly complex custom functions.
grace has them all and more.
> My experience with things like gnuplot, matlab, octave (which uses
> gnuplot), scilab, grace, etc. is that they are no where nearly as
> interactive as you'd really like for efficiently processing and
> interacting with simulator data.
A powerful feature of grace is the grace_np library. With it a c program can
remote control almost all aspects of the GUI, while the GUI is still
responsive to user input. That is, you can zoom, pan and inspect data points
while the results slowly come pouring in from the simulation.
http://plasma-gate.weizmann.ac.il/Grace/doc/UsersGuide.html#ss6.2
> other important features like the ability to define custom grid lines
> (think Smith chart, Nichols chart, and I have at least one that as far
> as I know only I use)
There you've got a point. According to the user manual Smith charts have not
yet been ported from xmgr, and Nichols charts are not even mentioned.
However, I reckon, it would be easier by orders of magnitude to add the
desired custom grid lines to grace than rolling your own fully featured
waveform application with GUI, inter process communication and all.
> Another important feature in a general purpose
> simulation waveform viewer is to be able to define custom cursor readout
> transformations.
Again, compared to what is already there, this is a minor feature.
> So.... I'd say that especially in the opensource area, a good waveform
> viewer is not reinventing the wheel. It is time to make a round one
> instead of the existing square ones!
IMHO, you underestimate the effort to get were grace and gnuplot already
are. The existing wheel is not square, but a fully functional sports utility
vehicle. You just need to add a few extra levers and you have an ideal
versatile simulation waveform viewer plus the benefit to produce publication
quality printouts.
That's the beauty of open source -- No need to start from scratch if an
application does almost, but not quite fulfill your requirements.
---<(kaimartin)>---
--
Kai-Martin Knaak
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