dimitris kalamaras

mathematics, social network analysis, free software…

Great Movies: District 9

District 9 is one of these movies that tell you a lot of real-world stories using exotic, if not superficially irrelevant, metaphors. In this case, the metaphor is simple: aliens have come to our planet, but without a clear purpose (peaceful or not). Rather, an alien mother-ship appeared over a South African city one day in 1982 and stayed there until the humans decided to enter and investigate what’s in there. What they found was thousands of alien insect-like beings without a leader, without food, without something to do or go. They looked… stranded thus the human government decided to confine them initially in a camp, called District 9, just outside the city…

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How to get free signed SSL Certificates and setup secure domains in Apache and Debian

This how-to describes the process to obtain 100% free, signed SSL Certificates from StartSSL.com and configure Apache in Debian to use these SSL certificates in your virtual domains, so that people can access your site(s) through https (i.e. https://example.com) without ever having the browser tell them the scary “this site isn’t trusted” anymore.

Before you start, you will need:

  • One or more of your functional domains which point to a server you own and have root access to. In this tutorial I’ll be using my wife’s supersyntages.gr as testbed.
  • A browser, for this tutorial Chrome, although you might prefer Firefox (see below why).
  • Root access to your server with Debian and Apache installed, with the above domains configured as VirtualHost.
  • The openssl package installed in your computer.
  • One of the following emails configured in each of the domains you want to include in the SSL certificates:
    [email protected]
    [email protected]
    [email protected]

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SocNetV v2.1 “fixer” released

Your favorite social network analysis & visualization free software project, Social Network Visualizer, has released a new version. SocNetV v2.1 has the quite eloquent codename “fixer” and it is available for Windows, Mac OS X and Linux from the project’s Downloads page. See some nice screenshots of SocNetV in action.

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SocNetV 2.0 released, built for stability & speed! – New features galore

I am happy to announce a new major release of Social Network Visualizer (SocNetV), the Social Network Analysis software. SocNetV v2.0 comes with a major code overhaul for stability and performance boost, improved GUI with a new panels layout, and nice new features for easier social network analysis, such as separate modes for graphs and digraphs, permanent settings/preferences functionality, edge labeling, recent files, keyboard shortcuts, etc. Also there are improvements in Force-Directed layouts, i.e. Fructherman-Reingold. The new version supports Windows, Linux and Mac OS X. Binary installers and source code packages are available from the project’s Download page. See below a walk-through of the new features.

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Bovary.gr goes online – A new digital experience for women


Bovary.gr is a new digital experience. A well-designed responsive website in Greek about women and their interests: fashion, beauty, art, design, healthy living and having fun.

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Build a static Qt5 for Windows by compiling from sources

By default the Qt5 libraries distributed from qt.io are dynamically linked. This means that every Qt app dynamically references and uses the Qt prebuild libraries (.dll or .so) it depends on. So in order to deploy your Qt app to your users, you need to find the relevant Qt libraries and distribute them as well (or make sure all other PCs have exactly the same Qt environment as your development PC), which is a pain. That is why it’s easier to build a static version of your application – one single  standalone executable with all libraries included inside. But to build a standalone executable of an app you need a static version of Qt libraries. If you target Windows 7/8, you might want to use the Powershell described in qt.io documentation to build a static Qt for Windows, but you can also compile a static Qt5 from scratch on your own. And no, it’s not that difficult…

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SocNetV version 1.9 is here, with LU decomposition and a Qt showcase!

Another release has just emerged from the depths of the Social Network Visualizer project! The new version 1.9 fixes important bugs and brings a vastly improved matrix inverse algorithm, thanks to the newly implemented LU decomposition. Of course, the new algorithm speeds up all other routines which depend on the inverse of a matrix, such as the Information Centrality algorithm.

Also, SocNetV v1.9 brings a revamped -and corrected- PageRank Prestige routine. Up to v1.8, the PageRank algorithm was using the original Page&Brin formula which lead to somewhat different results compared to other SNA applications. From this version, SocNetV uses the correct formula and computes comparable results (yes, we tested :)).

Source code, Windows zipped executables, Mac OS image and binary packages for major Linux distributions are as always available from the project’s Downloads page. Have fun with the new release!

Also, I am happy to report that the Qt project has added SocNetV to its ‘showroom’ page, along with many other nice Qt applications. There is also a showroom page dedicated to SocNetV with nice screenshots and a brief description of the application. Kudos to Kojo Tero, of Qt Company, for this!

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