Geogebra Miscellancies
Terminology
I've been wondering for a while what to call the little visualisations that I generate from time to time. I've seen quite a few terms used on different sites: interactivities, applets, worksheets, animations, miniworlds, interactive environments, etc. Now I can add another one: mathlets. I wish we could just pick one term and stick to it. For the rest of this post I'll refer to them as gromits.
Links
Elisha Peterson has created a number of interesting Geogebra gromits which are worth exploring, as well as a nicely written tutorial explaining how to generate an interactive Cobweb Diagram using Geogebra.
The Tools section of the Geogebra wiki is slowly building up a decent collection of Geogebra tools. The Tetris tools are particularly fun!
Splines
On the topic of tools, and following on from my earlier post on curves and splines, here's a Geogebra tool which implements a Catmull-Rom spline: cr-spline.ggt. Example gromit:
Frustrations
I've been trying to delve into some of the new matrix capabilities of Geogebra 3.2, and I'm getting quite frustrated! They don't seem to be particularly well integrated into the rest of the system -- for example, I've been trying for about 30 minutes now to figure out how to 'extract' the number from a 1x1 matrix (represented by, for example {{-4}}), so that I can calculate with matrices and display the results. Element[] would be the obvious tool, but it just returns 'undefined'.
Re: Terminology section, the term “mathlets” — To be fair here, the term “mathlets” is and was always intended to be pretty generic. The term originally referred to Java applets for math explorations, but these days includes Java, Flash, PHP, even Excel scripts, anything that gives an interactive online experience for some topic in math. Markus Hoenwarter’s article was just pointing out that GeoGebra is a particularly easy and convenient way to generate mathlets. If you want to refer to GeoGebra mathlets as “gromits” (in reference to an animated dog perhaps?), that’s fine, but the term “mathlets” isn’t going away. See the list of Developers Tools in the Developers area of Loci (the successor to JOMA), at the link I gave as my website (which is actually the Loci website), for lots more convenient ways to build mathlets.
Tom Leathrum
23 Apr 09 at 4:18 pm
Try:
Element[Element[matrix1,1],1]
ps GeoGebra 3.2 is out now :)
Michael Borcherds
3 Jun 09 at 2:33 pm
Michael,
I worked out what I was doing wrong (counting from 0 instead of 1, a legacy of C programming, I suppose). So now the only problem is that I don’t particularly like the Element[] notation. matrix1[1][1] would be much better :).
Also, are you sure that 3.2 is out now? I know there is a release candidate, but the Webstart and Download options on the Geogebra site still link to version 3.0. I look forward to seeing the final version when it does appear!
Jon Ingram
3 Jun 09 at 2:53 pm
http://code.google.com/p/geogebra/downloads/list
Michael Borcherds
4 Jun 09 at 9:32 pm
Great — I see the Geogebra website has been updated as well. Time for me to sit down and get used to the spreadsheet feature…
Jon Ingram
5 Jun 09 at 11:05 am