KSEG Free Interactive Geometry Software

Update: May 1, 2007 -- Mongolian

Batnasan sent me a translation into Mongolian.

Update: Februrary 3, 2006 -- KSEG 0.403 and Traditional Chinese

I finally got around to a bit of maintenance on KSEG: it now uses qmake for building and should build on Qt 3.x without the compatibility headers.

Yao Chang-Li sent me a Traditional Chinese translation and help file. It is included in the .403 file.

Update: May 15, 2005 -- KSEG in Chinese

Xu Xianghua kindly contributed Chinese translations of the KSEG UI and the help. Download the UI translation here and the help here.

Update: July 3, 2004 -- KSEG 0.401 for Windows!

By popular demand, despite my dislike for microsoft, I've ported KSEG to windows using the old Qt noncommercial version 2.3. The source is uglier and there are some bugs not in the Linux version. Download the whole thing here (it should run out of the box).

Sample Output

Images (not screenshots--those are below) of a well-known theorem and a strange locus, both exported with KSEG:


KSEG is a Free (GPL) interactive geometry program for exploring Euclidean geometry. It runs on Unix-based platforms (according to users, it also compiles and runs on Mac OS X and should run on anything that Qt supports). You create a construction, such as a triangle with a circumcenter, and then, as you drag verteces of the triangle, you can see the circumcenter moving in real time. Of course, you can do a lot more than that--see the feature list below.

KSEG can be used in the classroom, for personal exploration of geometry, or for making high-quality figures for LaTeX. It is very fast, stable, and the UI has been designed for efficiency and consistency. I can usually make a construction in KSEG in less than half the time it takes me to do it with similar programs. Despite the name, it is Qt based and does not require KDE to run.

KSEG was inspired by the Geometer's Sketchpad, but it goes beyond the functionality that Sketchpad provides.

Languages so far:


You will need Qt 3.x. If you don't have it, go to http://www.trolltech.com.

Although I develop KSEG in Linux, people have compiled it under Mac OS X and FreeBSD. For Mac OS X 10.3 and later, Markus Bongard built a standalone binary installer for KSEG, which also includes Qt. Get it here (about 5 MB download).

Download KSEG v0.403:

Here is the source. If you look around on the web, you should be able to find RPM's and other packages.

Here is the windows executable, version 0.401, and the ported (read: mutilated) source.

Current Features:

(features in italics are those that make KSEG special :) Suggestions? Never hurts to tell me your thoughts.

Screenshots - click to enlarge


Click on screenshot 3 to read more about it.



SEG started out as a little DOS program (in DJGPP) back in 1996 because I didn't want to pay $40 for a copy of Sketchpad. It was my first real C++ project and I made many design mistakes. Then I rewrote it under Windows and it was way better-fast, very stable, flexible and easy to use. I have successfully used it to generate the idea and write my highschool senior thesis (on chaotic dynamics of a family of geometrically-defined functions) and have played around with it a lot. Finally, I rewrote SEG a third time for linux (calling it KSEG because initially it was a KDE project--but I found the KDE API's were changing too fast for me to keep up), using my experience with the previous two designs. It has gone from a program for my personal use into a real piece of interactive educational software. Although I know that it is being used in education, I have heard few details about the experience, so please, if you use KSEG for teaching math in a school or college, write me about it.

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