[titaniumtown]

Desmos is the best, free (as in cost) and easily accessible graphing calculator out there. I wish it was opensource though. I've even tried to make an alternative and it's really hard to match their functionality (or I'm just inexperienced). I hope an opensource alternative crops up.

Edit: Seems there has https://www.geogebra.org/

[namibj]

GeoGebra is the closest I know, at least when limiting to copyleft [or theoretically the SQLite model would be fine, but it's pretty unique in dependability and selflessness for open source projects not subject to copyleft] "middle/high school (constructive?) geometry & function graphing teaching aid" classroom-grade robustness: bored & curious children are somewhat creative in their play/"(ab)use" of teaching/classroom software: buggy/anti-intuitive software can't survive the combination of:

- bored curious children playing around, bright and capable curious children exploring (way) beyond what the teacher explained, - normal students just getting by with the topic and relying on the software to aid their subject matter comprehension, - and teachers trying to plan lessons around it where they have to rely on it not needing a tutorial because there wouldn't really be time for such in the curriculum schedule.

[Xerox9213]

One of my favourite things about (desktop) Geogebra is its ability to export to tikz. Making complicated geometric shapes in a latex file can be done so easily with Geogebra. Perhaps not as elegant as Castel, but still quite nice.

https://castel.dev/post/lecture-notes-1/

[BD103]

Desmos does have a Github page, but unfortunately the main codebase is not public. Their API docs are well written, though, so it's really easy to embed Desmos into your site.

[^1]: https://github.com/desmosinc

[^2]: https://www.desmos.com/api/v1.8/docs/index.html

[omneity]

I've been using Geogebra since it was recommended to me by my high-school math teacher, what feels like almost a century ago.

It never disappointed!

Desmos looks like a solid spiritual successor, if it wasn't closed source.

[soegaard]

Commercial usage og Geogebra needs a license.

https://www.geogebra.org/m/pR5DME5S#material/yumfrbjr

I don't understand how their license and the GPL can co-exist?

[Someone]

https://www.gnu.org/philosophy/selling.en.html: “we encourage people who redistribute free software to charge as much as they wish or can”

Also, the engine is GPL-licensed, but the installer isn’t. https://www.geogebra.org/license#FAQ:

“How is GeoGebra licensed?

We license the different component parts of GeoGebra differently depending on their origin (authorship) and depending on your intended use of GeoGebra (see also next question)

- the source code is licensed under the GNU General Public License to ensure consistency with the various other pieces of software and libraries which are used within the GeoGebra source code (for a complete list of which see: https://wiki.geogebra.org/en/Reference:Sources_For_Used_Libr...).

- the GeoGebra installers (for various platforms including Linux, Mac OS, Windows, Android, iOS) and our web services (including GeoGebra Materials platform) are made available under our own licensing terms which have been drafted by an experienced law firm. We allow you to use the installers and web services for non-commercial purposes only provided you acknowledge GeoGebra; and

- the GeoGebra language files are made available under a Creative Commons license, which allows non-commercial use of these files.

Thus, there are really many different licenses involved in the background.”

I also noticed that one of their non-free options allows you the use of their logo. IANAL, but I don’t think the GPL automatically allows you that.

[SAI_Peregrinus]

Simple: don't accept outside contributions without a CLA. GPL doesn't ever restrict the copyright holder(s).

[knlje]

I've been using GeoGebra for years. I have tried Desmos twice but couldn't immediately spot the differences. What are the benefits of Desmos over GeoGebra?

[lights0123]

Desmos has a far smoother UI. Geogebra will often convert equations into its own format after clicking away from the equation editor, and if you mistyped or want to change the structure you must erase and re-type the whole thing—for example, typing f(x) will convert the equation into its own format where you can't edit parameters or the function name. Desmos leaves your input as text, allowing you to change input at the character level. From my high school experience where both were used frequently, a lot of frustration was expressed with Geogebra where missing a parenthesis forced you to re-type the entire equation since it often assumed the bulk of your equation was a parameter, and there was no way to correct it.

[nsajko]

> frustration was expressed with Geogebra where missing a parenthesis forced you to re-type the entire equation since it often assumed the bulk of your equation was a parameter, and there was no way to correct it.

I believe this may simply be a case of not knowing Geogebra well, or it's simply caused by differences in taste/being accustomed to a single user interface. In my experience, Geogebra offers the ability to edit the source of any object after selecting its settings. So it was just two clicks away.

This is Geogebra the Electron app, though, I think there's also a Web app and I think there was also a Java app some time before.

[titaniumtown]

I haven't heard of GeoGebra before! Really cool. Thanks for pointing that out.

[drsopp]

I just want to chime in on Geogebra. I used it (was more or less forced to) when teaching math in high school for about 12 years. It is great for guided exploration, but it is very buggy. I am confident many students must have lost points in their math exams because of some of those bugs.