dimitris kalamaras

mathematics, social network analysis, free software…

Category: Mathematics (Page 1 of 2)

The new features in versions 1.3 and 1.4 of SocNetV

Over the last weeks, the Social Networks Visualizer (SocNetV) project has released two new versions which brought useful new features and of course a lot of bugfixes. The latest v1.4 closed even 4 years old bugs!

socnetv-v1.4-erdos-random-social-network

socnetv-v1.4-erdos-random-social-network

The strongest new feature of SocNetV is multirelational editing. You can now load or create a social network on the canvas, for instance depicting the friendship ties between kids in a classroom, and then add a new relation (Cltr+Shift+N) which it might depict i.e. “likes” between pairs of the same clasroom kids. And you can be do this very easily as we will demonstrate in this article.

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SocNetV version 1.2 released with lots of goodies!

A new version of SocNetV, the cross-platform tool for social network analysis and visualization, has been released. Version 1.2 brings a major GUI overhaul, a new conceptualization of “prominence” measures, new importance and reachability measures, many new visualization layouts based on the new indices, and fixes a slew of bugs (see below).

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Math and Algebra software you can’t miss in Linux…

Yesterday, I was searching for some nice mathematics applications, mainly for computer algebra, in Linux and here are my two main conclusions.

  • First, there are hundreds of math programs and libraries out there for any need!
  • Second, try to stick with Debian-based distros, or else you ‘ll end up compiling the universe.

In the beginning, I had not exact idea what I was searching for, but to be honest I would love to have something like Mathcad (which unfortunately is commercial and not open-source). Unfortunately, I don’t believe there is such thing in Free Software, at least for the moment.

Nevertheless, after a little search with apt-cache (using Debian unstable), various applications came to my attention.

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Sparse Linear Systems Solver With SOR

This is a very simple Pascal program I wrote in mid 1990s, which solves a sparse NxN linear system using the Succesive Overrelaxation Method (SOR), which in turn is based on Gauss Seidel Method.
Both methods are iterative.

N is initially set at maximum …64.
You need the W factor for the SOR to complete successful. The theory assures us that it must be W=1.062.

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Tridiagonal Linear System Solver

This Pascal program is usefull in solving large tridiagonal linear systems. An example is the systems emerging from numerically integrating parabolic PDE’s by Finite Differences method.

It was ported to Turbo Pascal from a Fortran 77 program.
Its usage is very simple. All you have to do is to enter dimension of the system and the data, ie the three diagonals and the constant vector. Have fun…

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Horner Value Finder

This Pascal program finds the value of a Nth order polynomial:
a_{n}x^{n}+a_{n-1}x^{n-1}+cdots+a_{1}x+a_{0}
implementing Horner method without using any complex arithmetic in Fortran 77.

Obviously, it can find complex values, for complex x’s, but without complex arithmetic.
The program also uses ANSI codes to clear screen.

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Root-o-matic

This little Fortran program, originally written in DOS, uses the arithmetic sequence x_n+1={1/2} x_{n} + A / x_{n} to find the root of A.

All you have to do is to enter A and a guess value x_0

Caution: This program is very old; it uses Escape codes to clear the screen. In DOS, it needs the ANSI.COM driver. I haven’t test it on Linux 😉

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