This post is for people who are no longer satisfied with Dropbox and want to migrate their data to an alternative cloud storage service. I’ll demonstrate how to configure Dropbox to synchronize the files down to a local drive. The post is based on windows 10 and on dropbox-client (115.4.601) as of February,9th 2021, the… Read more How to get rid of Dropbox

## Find optimal Solution to Knapsack Problem with Linear Programming in R

In another post I demonstrated how to develop a heuristic to solve the knapsack problem. We managed to solve the problem quite well and had an optimality gap of about 1%, that is, our solution was 1% away from the optimal solution. Here I’d like to demonstrate, how simple it is to solve the Knapsack… Read more Find optimal Solution to Knapsack Problem with Linear Programming in R

## Solve Knapsack Problem with Heuristics in R

In this post I’ll show a way how to solve the Knapsack Problem applying a simple greedy improvement heuristic and how to implement it in R. What is the Knapsack Problem? On Wikipedia, you find the following definition: “The knapsack problem is a problem in combinatorial optimization: Given a set of items, each with a weight and a… Read more Solve Knapsack Problem with Heuristics in R

## Ode to a Legend of the Eighties – The Commodore 64

It was the machine one wanted to own as a boy back in the eigthies, long before the Amiga had been acquired by Commodore Inc. – the Commodore 64. At that time, PCs were presenting monochrome character-art pictures, games had to be played using the cursor keys and from time to time one could hear… Read more Ode to a Legend of the Eighties – The Commodore 64

## A Sudoku Solver in a few Lines of Code – Or the Power of Recursive Programming

In this post I want to demonstrate the power of recursive programming by programming a sudoku solver in Python. The complete sourcecode can also be downloaded here. Although I like solving Sudokus by hand, I’m far away from being a professional Sudoku solver. Usually I get the medium-ones solved, however, since I always want to… Read more A Sudoku Solver in a few Lines of Code – Or the Power of Recursive Programming

## Fun with Mandelbrot

I’ve always been intrigued by the Mandelbrot set and the nice images one can render with just that simple recursive formula z=z2 + c. Back in the eighties I rendered images in 320×200 pixels on my Commodore 64, then on my Amiga 500, later on a Macintosh and finally on my subsequent PCs. Where I… Read more Fun with Mandelbrot

## Switch Github Repository from https to ssh

Since github.com is about to disallow basic authentication using login and password over http/https connections, you should switch to connect via ssh providing a public ssh-key together with a passphrase. In this post I describe the steps necessary when using git for windows, however the steps are probably more or less identical if you’re running… Read more Switch Github Repository from https to ssh

## Open Windows Explorer from shell and vice-versa

If at work you “have” to work with windows clients and are using linux shell-like tools like git, you probably know this problem: You want to open a shell from the Windows File Explorer, then do some actions, change directories and then again open a Windows File Explorer from the shell at your current location.… Read more Open Windows Explorer from shell and vice-versa

## Graph Notation

There are different types of graph notations. Here I’d like to present a nice and compact way in the form of a Vertex Lists and Edge Lists, which I came across during my studies at the MSE in Zurich. [Note: All graph images shown in this post have been taken from graphical representations of graphs… Read more Graph Notation

## Solve TSP Instance using Google OR-Tools

If you happen to have to solve TSPs or some special type of VRPs – i.e. capacitated or with timewindows and other constraints – you might want to have a look at Google OR-Tools. The library contains a wide variety of heuristics for different problems primarly based on google’s excellent constraint programming solver. The library… Read more Solve TSP Instance using Google OR-Tools