## Making “Slice” Pointfree

Let the Haskell function slice be defined as

slice :: Int -> Int -> [a] -> [a]
slice from len xs = take len (drop from xs)

It takes to integral values, marking the beginning and the length of a sub-list, which is sliced out of the third parameter (a list). Applied to strings, this function may be known as substring. Here are some examples, illustrating what it does:

Prelude> slice 2 3 [0..9]
[2,3,4]
Prelude> slice 2 10 [0..9]
[2,3,4,5,6,7,8,9]

The goal is, to make slice pointfree, i.e. write it as slice = ..., and thereby illustrate the systematic approach of doing so. Continue reading Making “Slice” Pointfree

## [Paper Recap] Multiple Hypotheses Prediction

The paper Learning in an Uncertain World: Representing Ambiguity Through Multiple Hypotheses was publish by Christian Rupprecht et al. in late 2016. The authors propose a training technique for machine learning models which makes them predict multiple distinct hypotheses. This is an advantage for many prediction tasks, in which uncertainty is part of the problem. In this article I am going to summarize the paper and name further thoughts. Continue reading [Paper Recap] Multiple Hypotheses Prediction

## Digit Span Test (Online Tool)

The digit span test is a way of measuring the storage capacity of a person’s working memory: A testperson is visually or auditorily exposed to a sequence of digits one after the other. Right afterwards, the test subject has to recall the correct digits in the same order. Most people manage to recap around seven digits. I have written an online tool that lets the user determine their digit span test score. It is available at the website tools.timodenk.com/digit-span-test. Continue reading Digit Span Test (Online Tool)

## Graph Theory Overview

In the field of computer science, a graph is an abstract data type that is widely used to represent connections and relationships. This post gives an overview about a selection of definitions, terms, and algorithms, which are related to graphs. The content was put together during preparation for a theoretical computer science test at Cooperative State University Baden-Württemberg and is mostly taken from either Wikipedia or lecture notes. Continue reading Graph Theory Overview

## Observing the ISS from Earth

The International Space Station is orbiting our planet since 1998. One orbit takes only approximately 92 minutes and the ISS is sometimes visible at the night-sky. To the naked eye it looks like a bright star crossing the night sky in just a few minutes.

In April 2017 I was visiting my uncle in Almeria, Spain. He has a nice telescope and we were wondering, whether it would be possible to recognize the International Space Station’s shape through the telescope. As it turned out it is possible but not easy: The primary difficulty was to keep the rapidly moving ISS within the telescope’s field of view. Additionally, the video output was very shaky, which made comprehensive post-processing necessary. Continue reading Observing the ISS from Earth

## Get into Orbit Without Lateral Acceleration

When I was about 6 years old, my dad explained to me that there was no possibility to shoot something right into orbit from the Earth’s surface. He said it was always necessary to accelerate sideways to reach orbit. At that time I did not really understand what he meant. However, later in physics class I did and I figured what he had told me was true. Now, 13 years later, I came up with a new thought: The Earth’s rotation adds lateral velocity to objects launched from its surface. This is also the reason why satellites, the ISS and pretty much every artificial object flying around Earth, orbits Earth counterclockwise and also, why most space flight organizations / companies launch their spacecrafts from locations as close to the equator as possible. Continue reading Get into Orbit Without Lateral Acceleration

## Memorize the Elements of the Periodic Table Right on Your Wrist

This Android Wear app shows the chemical elements of the periodic table. Starting with Hydrogen you can continue with a simple tap on the center of the screen. Before you do that, you should think of the name of the following element. What comes after Hydrogen (H)? Continue reading Periodic Table Trainer (Android Wear)

## Guided Tour at CERN

On August 24th 2016, I took a guided tour for individuals at the European Organization for Nuclear Research (CERN, Conseil Européen pour la Recherche Nucléaire) headquarters in Geneva, Switzerland.

This post is about that kind of tour. So what did we do at the research organization that operates the largest particle physics laboratory in the world? Continue reading Guided Tour at CERN