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Software Pictures Contact

Dear Visitor

The webpage has moved to

http://philagathos.npage.de/ open

Here you can still find information about some algorithmic stuff and small applications.

Java Applications + Applets

Getting started

All programs introduced on this webpage provide not more than an installed Java Runtime Environment (JRE) version 6. Latest versions for all popular operating systems can be downloaded at http://java.sun.com open. After the JRE has been installed each of the programs can be started via double click; no further installations are required. Everyone may use each of the following programs for free, but at own risk.

Vigenere Cipher

A tool to code/decode texts using the Vigenere cipher. As both the Friedman Test and Kasiski Test are implemented, one can also try to reconstruct the key only on the basis of a ciphered text.

Start Applet

Download (as application): save

Travelling Salesman Problem / Ant Colony Optimization

A simulation of an ant colony solving the Travelling Salesman Probelm. The program simulates artificial ants, spilling pheromone on the edges of a city-graph while they are moving from one city to another until a tour is complete. After all ants have completed their tour through the graph, the ant with the shortest tour updates the pheromone level of the corresponding egdes and the process starts again. Consequently shorter egdes will receive more pheromone per time than a longer ones. As ants prefer edges with a high pheromone content to weaker marked ones, more ants will choose those edges that provide a higher pheromone level. Due to this positive feedback effect a short tour through the whole graph will arise after some time. Even though there is no guarentee to receive the shortest tour, the results are often good approximations to the optimum and they are much better than results from 'greedy' algorithms like the nearest neighbor heuristic. The implementation follows an idea of M.Dorigo and L.M.Gambardella, which was introduced in Ant colonies for the travelling salesman problem open, BioSystems, 1997.


Download: save

Predator Prey Simulation

The program simulates a simple food chain between hares, wolves and border-bears (type: Bruno) on an island. Several parameters like maximum ages, breeding probabilities and stress can be changed. The basic idea is that in every time step each animal moves randomly one field left, right, up or down. If hares and wolves clash at a common field, present hares will vanish and the present strengthend wolves will be allowed to reproduce. Hares, on the other hand, reproduce in each time step with a constant rate. As their food source is unbounded, they cannot starve. Bears devour everything, except other bears and hunt only near the edges of the island. As they neither die nor reproduce, their number is constant during the whole simulation. Properly chosen parameters will result in a stable system, which has reached its biological balance, as soon as the population graphs of the two species form two phase-shifted sinusoidal oscillations.


Download: save

Polynomial Function Analyzation

The program computes the characteristic values of polynomial functions up to a degree of six. Beside all derivatives of the function, all roots, extreme points, inflection points and inflection tangents are presented. The graph of the function and, if desired, the function's first three derivatives can be plotted.


Download: save

Computing determinants / Solving systems of linear equations

The program can be used either to compute the determinant of a square matrix or to solve a system of linear equations, which consists of n equations with n variables. The coefficients can be written both in decimals and in form of a fraction, so that writing 0.5 or 1/2 is possible. The system is solved recursively by the Cramer-Rule. This method is easy to implement, but it is probably the most inefficient way to solve systems with more than three variables. Hence the program was mainly designed as a benchmark for the CPU's arithmetic unit. However, a modern computer should be ready in not more than a minute for n=10.


Download: save

Scientific Calculator

Yet another freeware calculator...
Basic features:
-basic computations on arbitrary huge numbers;
-sine, cosine, tangent; arcus, hyperbolic and area hyperbolic mode; degree, radian and gon;
-logarithms: ln and log;
-constants: e and π;
-memories to store temporary results and a storable history containing the previous 100 computations;
Special features:
-solving quadratic functions: ax2+bx+c=0
-extended Pythagoras: √(x12+...+xn2)
-solving systems of linear equations with two variables;
-mean, variance and median of data series;
-binomial coefficients and n! in full length.


Download: save

Sudoku Solver / Creator

The program finds the missing numbers for any Sudoku task, but it can also be used to create new Sudokus. Each Sudoku sheet can be saved in form of a HTML file.


Download: save

Saprobienindex-Rechner zur Bestimmung der Gewässergüte

Dieses Programm berechnet nach Eingabe der gefundenden Indikatorganismen den Saprobienindex eines Fließgewässers und ordnet es anschließend in eine von sieben Güteklassen ein. Zusätzlich zur Güteklasse ermittelt das Programm noch die Validität des Ergebnisses. Sie liefert über die Anzahl der gefundenen Arten und die Streuung ein Maß dafür, wie gut der ermittelte Saprobienindex zu der zugehörigen Güteklasse passt. Alle Ergebnisse lassen sich mit zusätzlichen Informationen über das untersuchte Gewässer abspeichern.


Download: save

Sonnenaufgangs und Sonnenuntergangs Rechner

Dieses Programm berechnet zu (fast) beliebigen Orten auf der Erde den Zeitpunkt des Sonnenaufgangs und des Sonnenuntergangs, sowie die daraus resultierende Taglänge. Verwendet wird hierzu eine Näherungsformel mit einer Genauigkeit von etwa ±5 Minuten open. Der Ort kann entweder aus einer umfangreichen Liste ausgewählt werden oder die Koordinaten werden manuell eingegeben. Es werden alle Orte unterstützt, deren nördliche Breite zwischen ±60 Grad liegt.


Download: save


Some pictures ...




David Hübner
Ankerstrasse 10
39124 Magdeburg

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Last modified: 2009
© David Hübner 2007-2010

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