Handing over the reins

November 15, 2015

As some of you might know, I started the application Cantor in KDEedu a couple of years ago, since I didn’t want to rely on comercial computer algebra systems during my studies, and because all the free alternatives seemed to lack a decent graphical interface. Since then Cantor has grown to support all kinds of different mathematical languages due to numerous contributors from all over the world.

Unfortunately, lately I’ve found myself with less and less time to spend on Cantor especially since I’ve started working on my Phd. Luckily for me others have made sure that the project keeps going, and have for example ported it to KF5 etc.

So now I think its time for me to step down as the maintainer of Cantor, and hand over the reins to Filipe Saraiva, who has been with the project for a long time now, and was the main driving force behind the Python backends and the Frameworks port (among other stuff). So I’d like to wish Filipe, and the Cantor project all the best, I know he is up to the task, while I take on more of an observer role to its development.

Randa Results: New Maxima backend for Cantor

September 25, 2012

It’s been some very busy last few days here in Randa for the Cantor project, and today you’ll get the first big result in the form of  a completely rewritten Maxima backend. I’ve started the work on this a couple of weeks ago, and with the help of Martin I’ve finally been able to get it to a state that is (IMHO) quite remarkable and merge it into what will be KDE SC 4.10.

The old backend suffered from some weird design decisions I made in the early days of Cantor and my limited knowledge of Maxima, so it involved quite a lot of guesswork and magic to do its job. For example it used a separate instance of Maxima just to convert results into a latex-format. This of course caused a lot of problems and looking back I’m sometimes surprised it worked at all.

But not anymore! The new and all shiny maxima backend should not only be much more stable (i don’t seem able to break it(here at least (for now anyway)), with a lot less guessing going on behind the scenes, it also should be faster and it has a much higher code quality, hopefully keeping it maintainable for a long time. And the best of all, you get some new features with it as well. The Maxima backend now supports the Variable-Management-Panel so you always have all your defined variables and functions in view. Also this functionality allows the syntax-highlighter and the tab-completion to show your custom variables.

Thanks to everyone who made this possible by supporting the Randa meeting. Enjoy the new old backend. The Meeting is only a little more than half-way over, so expect a lot of other interesting things to happen.

Formulas inside Cantor

August 25, 2011

I haven’t been overly active in KDE lately. I finished my bachelor degree this semester and that didn’t leave much time for KDE (or real-life for that matter). But now I finally have time to do some hacking again. And with this post I’d like to introduce a new feature I’ve been working on for the last days: Formulas inside Cantor.

Since the beginning Cantor had the possibility to typeset the results of your calculations using LaTeX. A bit later it got support for text entries that can be used for better documenting the calculations you are doing, but until now it was not possible to have nice formulas inside your text.
I’ve had more or less finished patches for this feature done by other contrybutors lying around for quite some time now, but somehow they never got to a point where I could integrate them. (Sorry for that guys). Until now. I’ve rewritten some things, cleaned up others, and rewrote some minor things inside Cantor to make it fit better and now it finally landed in master.
I’ve added two ways you can add formulas inside your Cantor worksheets. For one you can just use a regular Richtext-Entry with all the simple formatting options it offers. If you want to add a formula, just insert your latex commands inside a pair of ‘$$’ (e.g. write $$\sum_{n=0}^{\infty}{\frac{1}{n^2}}$$) and it will be rendered and inserted inside your text once you evaluate the entry. If you want to edit it again, just double-click on the formula.
This is useful for small formulas with some text around them. For fancier stuff, I’ve also added a new type of entry that renders all its input using LaTeX and displays it. Again you can double click the entry to edit it again. In the following screenshot you can see this feature in action:
The whole thing is still in a pretty early stage, for example loading/saving these new things does not work correctly yet, but for now I’d really like some feedback on what you think about it, and more importantly: how the user interaction should be done, do you like the $$-thing, and the double clicks or should it behave differently? I’m open to suggestions.
So have fun, with the first new feature I coded in a while.

Cantor: New R backend in trunk

October 2, 2010

Just a short note:

the improvements to the R backend that were developed by Oleksiy Protas during this years Summer of Code have now landed in trunk.

The changes include Syntax Highlighting, Tab Completion and more.

Please give them some testing.

Something I am working on

September 16, 2010

I just wanted to post a Screenshot of one of the things I’ve been working on lately:

Some of you may recognize this as one of the most frequently requested features for Cantor: a Variable Management Panel

Most of the competitors seem to offer this possibility to interact with the defined variables in a worksheet, so Cantor shouldn’t be behind on this.

It shows all of the currently variables, you can modify their values or add new ones. Isn’t that awesome?

The code is still not in svn as I’ll probably still rework the API a bit, and I can’t promise which backends this functionality will be available in the end (at the moment only KAlgebra is used as a playground), but I’m looking forward to having this functionality ready in 4.6.

Cantor needs an Icon

August 30, 2010

Yesterday I realized that while Cantor has recently had its second stable release, and seems to enjoy a growing userbase, we are still using the default icon that comes with kapptemplate. That really should change for the, already pretty awesome, next release. Unfortunately my drawing and design skill are pretty much non-existent. So I rely on you to fill the gap.

Is there anyone out there who can come up with something that makes sense representing the app and just looks good?

I think we really can do better than this:

Cantor in 4.6 is gonna rock!

August 18, 2010

The last release of Cantor didn’t have many new things to show off. I was busy with university so it mostly just got minor bug fixes.

But for the next release you can expect a great amount of additional awesomeness. And the best thing? I didn’t have to code any of it!

All the cool new features were written by new faces.

– Text cells that can contain richtext

Cantor now has the ability to insert Text cells into the worksheet, so you can comment your calculations or just do some pretty headlines.

You can insert a great deal of RichText so if you want you can go completely nuts designing your new worksheets!

This one was written by Raffaele.

– Octave Backend

Octave is one of the leading packages for numerical mathematics and a great replacement for the proprietary MATLAB. Thanks to Miha and his Season of KDE project you now have the possibility to use it from within the beautiful Cantor Worksheet interface (isn’t that just cool?). It is already full featured with Syntax Highlighting, inline plots, Tab completion etc.

– improved R backend(*)

The R backend has always been the lost son under all the backends. I never used it that much so it never got to shine. This summer during his Google Summer of Code project Oleksiy decided to give this backend the love it deserves. Now this backend finally has all the features you missed when comparing it to the others (e.g Tab Completion or Syntax Highlighting). But it also gained some R unique features, for example up to now you only saw the normal output, you’d also have gotten when using the command line. That means boring Ascii-Art like tables. But not anymore, nowadays you get pretty tables integrated in the worksheet!

Those are only the most visible improvements. There are also quite a lot of under the hood changes going on at the moment, that will make Cantor faster, more flexible and overall a greater place to hack on.

Those are some really exciting times for Cantor. It’s developement team has basically grown three times the size it had last year (that was basically just me 🙂 ). So prepare for all the new glory that will be Cantor when 4.6 will be finally out next year. (And be excited for what new stuff we might come up with until then).

(*) The new R backend is not yet in trunk. It resides at /branches/work/cantor-soc/ but it will be merged soon.

Looking for help for R

March 6, 2010

As you probably all know, Cantor currently has 4 available Backends: Sage, Maxima, KAlgebra and R. While the first 2 are in pretty good shape, as they are what I mainly use, and KAlgebra is maintained by apol, the R backend of Cantor is still lagging behind.

It started out as an afternoon hacking rush, and hasn’t changed much ever since. Mostly because I don’t have much usage for it at the moment.

While it does support the basics (running a command and showing the results) it does miss a lot of the nice features, Cantor is offering, like Tab-Completion, Syntax Highlighting or Assistant dialogs.

The feedback I got for Cantor so far tells that quite some people want to use R as backend, so I feel a bit bad that it is only a second class citizen in the family.

So I’m looking out for some help making the R support as good as the other backends (or even better). If you are a developer with needs for a nice statistical app and looking for a new challenge, please drop me a mail, and join the Cantor development.

Introducing Cantor

October 20, 2009

This post comes a bit late, so some of you may already have heard the news: KDE Edu will ship a new application in 4.4: Cantor*.

Cantor is an application that lets you use your favorite mathematical applications from within a nice KDE-integrated Worksheet Interface, and offers assistant dialogs for commonly used functions like solving equations or integrating/differentiating a function. It currently has support for three Backends Sage, Maxima and R.

It is aimed to fill the gap, most free software math packages have, compared to proprietary systems: an intuitive to use graphical interface.

Some of it’s most important features are:

  • View of plotting results inside the worksheet or in a separate window
  • GetHotNewStuff integration to upload or download example worksheets
  • Typesetting of mathematical formulas using LaTeX
  • Backend aware syntax highlighting
  • Tab completion and integrated syntax help

This is how it looks:

Screenshot of Cantor

* It is named after mathematician Georg Cantor, the creator of Set Theory http://en.wikipedia.org/wiki/Georg_Cantor

About this blog

October 5, 2009


my name is Alexander Rieder, student at the Vienna University of Technology.

This Blog will be on my work inside KDE, and mostly on Cantor, a new Edu application in KDE 4.4 (Big announcement will follow)

So stay tuned