GCLC page

by Predrag Janicic


The original address of this page is: www.matf.bg.ac.yu/~janicic/gclc


new: new release: GCLC 7.0/WinGCLC 2007 ((c) 1996-2007) (28. January 2007)

new: join GCLC/WinGCLC Forum (January 2007)




What is GCLC? GCLC (from "Geometry Constructions->LaTeX converter") is a tool for visualizing and teaching geometry, and for producing mathematical illustrations. Its basic purpose is converting descriptions of mathematical objects (written in the GCL language) into digital figures. GCLC provides easy-to-use support for many geometrical constructions, isometric transformations, conics, and parametric curves. The basic idea behind GCLC is that constructions are formal procedures, rather than drawings. Thus, in GCLC, producing mathematical illustrations is based on "describing figures" rather than of "drawing figures". This approach stresses the fact that geometrical constructions are abstract, formal procedures and not figures. A figure can be generated on the basis of abstract description, in the Cartesian model of a plane. These digital figures can be displayed and exported to LaTeX files (or some other format). WinGCLC is the Windows version of GCLC and provides a range of additional functionalities.



  • DOS/Windows: GCLC 7.0/WinGCLC 2007 ((c) 1996-2007 Predrag Janicic); command line version (GCLC) and Windows version (WinGCLC) with graphical, multi-document interface, support for animations, traces, export to bitmaps etc. The archive includes manual files, sample files, LaTeX package gclc.sty, additonal tools etc. (available since 28.01.2007) 

  • Linux: GCLC 7.0 ((c) 1996-2007 Predrag Janicic); command line version (GCLC) manual files, sample files, LaTeX package gclc.sty, etc. (available since 28.01.2007) 


Author: GCLC/WinGCLC is being developed at the Faculty of Mathematics, University of Belgrade, by Predrag Janicic and, in some parts, by Predrag Janicic and his coauthors:

  • Ivan Trajkovic (University of Belgrade, Serbia) - coauthor of the graphical interface for WinGCLC;

  • prof. Pedro Quaresma (University of Coimbra, Portugal) - coauthor of the theorem prover built into GCLC;

  • prof. Konrad Polthier and Klaus Hildebrandt (Technical University, Berlin, Germany) - coauthors of JavaView -> GCLC converter).

  • prof. Pedro Quaresma (University of Coimbra, Portugal), Jelena Tomasevic (University of Belgrade, Serbia), Milena Vujosevic-Janicic (University of Belgrade, Serbia) - coauthors of support for XML.


Scope: Although GCLC was initially built as a tool for converting formal descriptions of geometric constructions into LaTeX form, now it is much more than that. For instance, there is support for symbolic expressions, for drawing parametric curves, for program loops, etc; a built-in theorem prover can automatically prove a range of complex theorems; the Windows graphical interface makes GCLC a dynamic geometry tool for teaching geometry, and other mathematical fields as well.

The main purposes of GCLC/WinGCLC:

  • producing digital mathematical illustrations of high quality;

  • use in teaching geometry;

  • use in studying geometry and as a research tool.

The main features of GCLC/WinGCLC:

  • support for a range of elementary and compound constructions, isometric transformations, and other geometrical devices;

  • support for symbolic expressions, second order curves, parametric curves, while-loops etc;

  • user-friendly interface, interactive work, animations, tracing points, watch window ("geometry calculator''), and other tools;

  • easy drawing of trees;

  • built-in theorem prover, capable of proving many complex theorems (in traditional geometry style);

  • very simple, very easy to use, very small in size;

  • export of high quality figures into LaTeX, bitmap, EPS (Encapsualted PostScript), SVG (Scalable Vector Graphics) format;

  • command line versions for DOS/Windows and Linux and the MS Windows version;

  • import from JavaView JVX format;

  • freely available (from http://www.matf.bg.ac.yu/~janicic/gclc and from EMIS (The European Mathematical Information Service) servers: http://www.emis.de/misc/software/gclc/).


Copyright notice: GCLC/WinGCLC is copyrighted and cannot be used in commercial purposes. However, you are free to use it in teaching, studying research and in producing figures and digital illustrations for non-commercial purposes.

Feedback welcome: If you download and use GCLC package, please let me know by sending an e-mail to janicic@matf.bg.ac.yu (Predrag Janicic); we will put you on the GCLC mailing list and inform you about new releases of GCLC/WinGCLC.

Please send us your comments and suggestions to janicic@matf.bg.ac.yu .Your feedback would be very much appreciated and would help in improving the future releases of GCLC.

If you used GCLC for producing figures for your book or a paper, we would be happy to hear about that and to get a copy.

Please send us your GCLC gems and we will put them on this page.

WinGCLC screenshot


History: GCLC/WinGCLC programs had several releases since 1996. and they have been used for producing digital illustrations for a number of books and journal volumes, and in a number of different courses.

What others said about GCLC/WinGCLC: "... program WinGCLC ... is a very useful, impressive professional academic geometry program.'' (from an anonymous review for "Teaching Mathematics and its Applications'')

References: More on the background of GCLC/WinGCLC can be found in:

  • P.Janicic and I. Trajkovic: WinGCLC --- a Workbench for Formally Describing Figures. In Proceedings of the 18th spring conference on Computer graphics (SCCG 2003), pages 251--256, Budmerice, Slovakia, April, 24-26 2003. ACM Press, New York, USA.

  • M.Djoric and P.Janicic. Constructions, instructions, interactions. Teaching Mathematics and its Applications, 23(2):69--88, 2004.

  • P. Quaresma and P. Janicic. Framework for the Constructive Geometry. Technical Report TR2006/001, Center for Informatics and Systems of the University of Coimbra, 2006.

  • P. Quaresma and P. Janicic. Integrating dynamic geometry software, deduction systems, and theorem repositories. In J. Borwein and W. Farmer, editors, Mathematical Knowledge Management (MKM-2006), volume 4108 of Lecture Notes in Arti cial Intelligence, pages 280-294. Springer-Verlag, 2006.

  • P. Janicic and P. Quaresma. System description: GCLCprover + GeoThms. In U. Furbach and N. Shankar, editors, International Joint Conference on Automated Reasoning (IJCAR-2006), volume 4130 of Lecture Notes in Artificial Intelligence, pages 145-150. Springer-Verlag, 2006.

  • P. Janicic. GCLC - A Tool for Constructive Euclidean Geometry and More than That. In N. Takayama, A. Iglesias, and J. Gutierrez, editors, Proceedings of International Congress of Mathematical Software (ICMS 2006), volume 4151 of Lecture Notes in Computer Science, pages 58-73. Springer-Verlag, 2006.









I am grateful to

  • Prof. Mirjana Djoric for the initial discussion which led to the first version of GCLC (1996);

  • Prof. Neda Bokan and other members of the Group for geometry, education and visualization with applications (mostly based at the Faculty of Mathematics, University of Belgrade) for their invaluable support in developing the WinGCLC package (2003);

  • Ivan Trajkovic, the main author of the graphical interface in WinGCLC (2003);

  • DAAD (Germany) for funding my visit to Konrad Polthier's group at Mathematical Institute of TU Berlin (2003), which I used for making a JavaView->GCLC converter. I also thank Konrad Polthier and Klaus Hildebrandt for their hospitality and their collaboration in developing this converter;

  • CIM/CISUC (University of Coimbra) for funding my visit to the Department of Mathematics, University of Coimbra (2005), which I used for developing the geometry theorem prover built into GCLC. I also thank prof. Pedro Quaresma for his warm hospitality and his collaboration in developing this prover;

  • Prof. Pedro Quaresma (University of Coimbra), Jelena Tomasevic, and Milena Vujosevic-Janicic, coauthors of the xml support for GCLC (2006);

  • Prof. Bruno Buchberger (RISC, University of Linz), for kindly inviting me to visit RISC and to present GCLC there (2006).

  • EMIS (The European Mathematical Information Service) for mirroring this page at http://www.emis.de/misc/software/gclc/ ) and other EMIS locations;

  • James Fry (New Albany, Indiana, USA) for careful revision of the GCLC/WinGCLC manual file and many useful insights and comments (2005);

  • Aleksandar Samardzic for his help in making Linux release of GCLC (2003/2005);

  • Colleagues which gave contributions and suggestions in earlier stages of development of WinGCLC: Nenad Dedic, Milos Utvic, Nikola Begovic, Ivan Elcic, Jelena Grmusa, Aleksandra Nenadic, Marijana Lukic, Goran Terzic, Milica Labus, Srdjan Vukmirovic, and Aleksandar Gogic (1999/2003);

  • Konrad Polthier (TU Berlin), Zach (Temple University, USA), Vladimir Baltic (University of Belgrade), Hristos Bitos (Greece), Aleksandar Gogic (DTA, Belgrade), Bob Schumacher (Cedarville University, Ohio, USA), Biljana Radovanovic (University of Belgrade) for useful feedback and suggestions on different versions of GCLC/WinGCLC.

  • All GCLC/WinGCLC users for their support, feedback and suggestions.

Predrag Janicic



GCLC gems:



Prof. Zoran Lucic (University of Belgrade): Euclid's construction of dodecahedron (2005)




Prof. Zoran Lucic (University of Belgrade): Archita's construction of cube doubling  (2006)




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