Posts about Computer (old posts, page 9)

I had my first computer with 5 and started C programming when I was 13. Then I made some simple websites using PHP which grew into ever more complex ones. In 2007, I created some Java applications, some of them are still among the portfolio on this page. While I was an intern at the DLR, I started to learn Python and IDL, which introduced me to matrix based languages. For the numerical methods lecture and especially my bachelor’s thesis I used C++11. During my master’s thesis I have learned Haskell for fun. Later on for my PhD thesis I also learned R and the Wolfram Language.

This section of my site is for articles about programming practices and performance tests. Also various stuff about computer hardware and software.


On my PC and my phone there are ample opportunities for notifications. Some of them are system notification like charge levels, but most of them come via applications. One could get a notification for every email, every instant message. Browsers can now relay notifications from websites to the user. On the phone you have messages, calls, reminders.

There are the maker and manager schedules. In short a manager works on a rather short time scale and does a lot of little decisions. The maker in contrast goes into the zone and works on a problem with deep concentration. Ripping the maker out of that concentration will result in a loss of a lot of time because they have to get back into the zone again. Notifications are interruptions that are easily turned off.

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Mein Supporterlebnis bei der Telekom

In meiner Wohnung habe ich 2014 mit einem Internetanschluss von Unitymedia angefangen, der hatte 10 MBit/s Download und 1 MBit/s Upload (im weiteren Text nur noch »10/1«) für 20 EUR/Monat. Irgendwas hat dort nicht richtig funktioniert, das Problem konnte nicht richtig identifiziert werden. Per Sonderkündigung durfte ich aus dem 24 Monate-Vertrag raus.

Wegen dieser Erfahrung habe ich bei Congstar einen monatlich kündbaren Vertrag gewählt, mit 16/2 Datenrate für 30 EUR/Monat. Immer mal wieder hatte ich geschaut, ob das nicht auch günstiger geht, allerdings waren die meisten günstigen Verträge von Telefónica. Deren Support wird ja immer als sehr schlecht beschrieben, mit ewigen Wartezeiten an der Telefonhotline. Also habe ich das erstmal gelassen.

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Tschüss DomainFactory

Im November 2014 bin ich mit meinem Webhosting von Strato zu DomainFactory (damals domainFACTORY) umgezogen. Dort habe ich mehr Leistung bekommen für einen vernünftigen Preis.

Juni 2015 habe ich dann den Tarif gewechselt, weil ich so viel Leistung gar nicht gebraucht hatte. Die Runterstufung kostete nochmal 10 EUR Einrichtungsgebühr, aber okay.

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The Pain of Watching TV Shows Legally

I prefer to do things in the legal way, and watching TV shows is no exception. It is different, however, in that here it actually is hard to impossible to do.

The most recent example is the show "The Expanse". Friends have suggested this show to me, and I finally gave in and subscribed to Netflix. There I happily watched the first two seasons in high definition. After I was through with it, I wanted to continue watching "The Last Ship". Although not quite on the same level, it has a little appeal. But "The Last Ship" is not featured on Netflix. The only way to watch it is to buy the DVDs (if available) or buy a whole season on Amazon for some EUR 25. That is quite expensive, especially if one is used a subscription model like with Netflix or Amazon Prime. And EUR 2.50 per episode is a bit much for this show.

Weeks later I read that "The Expanse" is being continued by Amazon. So I will have to get an Amazon Prime subscription to continue watching it? A friend asked me how I progress with the third season. "Third season? There are only two on Netflix!" I told him. Turns out that you can obtain the first ten episodes of the third season, but not on Netflix or any other streaming service available in Germany. I was made the tempting offer to get them in high definition, right there on a thumbdrive. But if the license holders do not want me to watch it, then I won't.

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Signatures Seem Useless

There are two types of signatures, the one written with a pen on paper and the cryptographic one. I want to argue that the former kind has many issues.

When I pay with my debit card in a store I occasionally have to sign a receipt. The cashier sometimes takes a look at my signature and compares it to the one on the back of the debit card. Sometimes they are not satisfied and want to see my ID document and just compare my face with the picture and the names on ID and debit card. The signature on the receipt is only checked if a charge is revoked with the bank and the supermarket has to find the receipt to show that it did nothing wrong. I presume that the issue is then settled in a court setting where a handwriting specialist appears as an expert witness and determines whether the signature is legitimate. Or the amount is not worth the hassle and the supermarket just takes the loss.

Signing a contract is similar. The company on the other side has no reference of my signature, so I can just sign however I like. Only when there is a serious issue the signature might be compared in a court setting. It becomes interesting when a contract is filled out on the computer and printed, then signed. Sometimes one does edits to the typed content and one should sign off these changes with a small signature or initials. This way the other side knows that these were made by me.

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Long and Wide Data Format

There are multiple ways of structuring data. Two sensible formats are the long and the wide data format. In this article I want to do the same problem in two different ways and show the relative merits.

As a task, we want to compute $pi$ using Monte Carlo techniques. We want to see the scaling of the precision and accuracy with the number of iterations. For the precision we need to compute an error estimate. This will be done with the bootstrap procedure, though here we can actually sample from the underlying distribution.

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MechWarrior Online Weapon Analysis

I played around with the weapons from MechWarrior Online in R. The following is created from an Rmarkdown document.

First we need to download the data from some website. There is one table which contains the columns of interest and seems reasonable to parse.

#url <- ''
url <- ''

weapons_orig <- htmltab(doc = url, which = "//th[text() = 'Damage']/ancestor::table")

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