[lm]azy http://lmazy.verrech.net books, computer science and ramblings Tue, 29 Mar 2016 19:59:53 +0000 en-US hourly 1 http://wordpress.org/?v=3.7.1 Early impressions of my RaspberryPi http://lmazy.verrech.net/2013/01/early-impressions-of-my-raspberrypi/ http://lmazy.verrech.net/2013/01/early-impressions-of-my-raspberrypi/#comments Sun, 20 Jan 2013 15:08:23 +0000 http://lmazy.verrech.net/?p=4095 Read more »

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Last year I ordered a RaspberryPi; I wanted to check out the hype and, who knew, maybe I’d get a decent media (or at least music) player out of it. The machine arrived right in time for Christmas, together with an SD card preinstalled with Raspbian and a USB power supply.

Wow, the CPU of this thing is slow. I was lucky to get the new version with 512MB RAM, I guess. Any CPU-heavy task feels extremely sluggish, be it aptitude, X or — beware! — watching videos. The GUI software package that comes with Raspbian is all but useless, too, so I soon decided to stick to a native terminal.

I was quite disappointed with the video performance which resembled a slide show; I had wanted to use the Pi as media center, after all. So I did some research and learned that there is apparently only one player which can harness the hardware video decoding capabilities the Pi has to offer: the OMXPlayer.

Turns out Raspbian with OMXPlayer does a better job of playing full HD videos than my gaming PC, and without the noise and barely any heat. Of course, you should not start X but run the player from shell (yes, that works!); not the most intuitive interface — and you have to change the terminal font if you use a big TV — but very efficient. Files are stored on an external HD connected to another PC which the Pi mounts via ssh. So far, I have not experienced any problems with this setup.

The only sore point has been the board layout; the connectors you can’t go without (Ethernet, USB, HDMI, AC) face three different directions, so the Pi is awkward to place if you want to run all cables to the back. Some minor annoyances are missing codecs, for example WMV, and a handful of inconveniences in OMXPlayer.

I have not yet tried using XMBC which is supposed to work well. Installing it on Raspbian does not seem to be straightforward; maybe I’ll try out Raspbmc on another card. Does anybody have experience with that?

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Back in January when I bought my ereader, I had doubts whether I would be able to find enough quality content to read on it, given that I don’t buy DRM which still dominates the market. By now I have found enough sources; in fact, I am not quite able to read it all. Here is what I have been reading, in arbitrary order.

### Commercial

• Baen Ebooks has a free library.
• Smashwords has many free titles; it is common for authors to give away extended prologues or even first volumes of series.
• The Firefox plugin GrabMyBooks allows you to pack any web content as EPUB ebook. I regularly do so with CACM and Flash Fiction Online.
• There are some books floating around the open source community. For example, I discovered Pro Git recently.

### Stallman-free

• Project Gutenberg offers English classics that have entered the public domain in multiple formats.
• Gutenberg DE is the German version. Sadly, there are no downloads, but you can grab the text.
• Project Runeberg is the Swedish version of Project Gutenberg. They have download as plain text and HTML which is easy to convert.

Over these last year or so, EPUB has been entering more and more publishing heads. I am particularly excited about Tor’s move to drop DRM; huge amounts of science fiction and fantasy are viable in electronic form now. Tor has a nerdy audience (both readers and authors) so maybe they felt more pressure than other publishers; let’s just hope that their example catches on.

Once tools for creating EPUB books become better, it will be increasingly simple to offer ebook versions of your content, be it fiction book, scientific article or tech tutorial. In my opinion, the phase of early adopters is past: with the spread of EPUB, ebooks have left the confines of big publishing houses behind and become a medium of the crowd.

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Richard L. Sanders: The Phoenix Conspiracy http://lmazy.verrech.net/2012/04/richard-l-sanders-the-phoenix-conspiracy/ http://lmazy.verrech.net/2012/04/richard-l-sanders-the-phoenix-conspiracy/#comments Mon, 09 Apr 2012 10:00:41 +0000 http://lmazy.verrech.net/?p=3874 Read more »

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 Story: Characters: World: Humor: Action:

Calvin Cross is a successful and loyal officer in Intel Wing, the Empire’s intelligence organisation. He is so good that he has been given his own command, the stealth frigate Nighthawk, despite the fact that he is only a half-citizen and therefore stuck at a junior officer rank. His latest mission has been to track down rogue warship captain Raidan who used his position to destroy civilian alien freighters without provocation. Raidan is tried by a tribunal and found guilty, but his motives remain unknown. The prisoner escapes under suspicious circumstances—hijacking a dreadnought in the process—and Cross is again ordered to find him. Cross suspects foul play as several facts do not add up and decides to investigate the underlying situation rather than hunting down the fugitive. While he tries to keep up appearances his mysterious opponents act to stop Cross and his crew no matter what.

Phoenix Conspiracy has a solid, but not brilliant setup. The futuristic world is very similar to ours despite the fact that humanity travels across space; culture and technology appear unchanged for the most part. It works well enough for this kind of story as the reader feels comfortable from page one and can completely focus on the intriguing plot. The conspiracy is nicely set up and the characters are likeable yet complex enough to feel real, including heart-felt emotion and sometimes funny, sometimes nerve-wracking conflicts. Only the ending seemed a bit too hasty and shallow for my taste; but then, this is only part one of a series so I will give Sanders the benefit of doubt, assuming the rabbit hole is deeper than it seems. Phoenix Conspiracy managed to captivate me and I had a good time reading it. I certainly look forward to the sequels!

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Pretty Math on Wikipedia http://lmazy.verrech.net/2012/04/pretty-math-on-wikipedia/ http://lmazy.verrech.net/2012/04/pretty-math-on-wikipedia/#comments Thu, 05 Apr 2012 10:00:08 +0000 http://lmazy.verrech.net/?p=3876 Read more »

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In the days of MathJax, the math images on Wikipedia look inferior by a huge margin. The MathJax guys got us covered; they provide a userscript1 that dynamically injects MathJax into Wikipedia sites2. It may load a little longer, but I think this is worth the wait:

Without MathJax

With MathJax

1. Userscripts are pieces of Javascript your browser executes on top of any website. Firefox users use Greasemonkey, others see here.
2. Make sure to change the @include to http://*.wikipedia.org/wiki/* so the script works on all Wikipedias.
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 Story: Characters: World: Humor: Action:

Harvey Barker is on a revenge trip in modern London, killing the people he holds responsible for his sister’s death. He is a professional assassin, but an unorthodox one: he kills using feng shui, manipulating chi and karma to kill his targets without anyone the wiser. But he is not careful enough this time. Detective Amanda Morgan can not shake the feeling that a couple of apparently tragic deaths are connected. Meanwhile, the remaining members of the group Harvey hunts down try to recover and strike back.

I needed to suspend a lot of disbelief regarding the manipulation of chi and karma. The concept seems confused at times, but experienced manga readers should have no problems accepting it. Hall’s prose is not perfect but good enough so it does not distract from his decent story. He builds a good amount of tension towards the end, finishing a very entertaining and thrilling book.

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Quick Images with TikZ http://lmazy.verrech.net/2012/03/quick-images-with-tikz/ http://lmazy.verrech.net/2012/03/quick-images-with-tikz/#comments Thu, 29 Mar 2012 10:00:27 +0000 http://lmazy.verrech.net/?p=3878 Read more »

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How do you create high-quality technical images for documents, your website or posts on Stack Exchange? I have used tools in an ad-hoc manner for a while and have become frustrated lately. Once you have used TikZ1 with $$\LaTeX$$ most other tools feel inferior. The only problem is: TikZ is a $$\LaTeX$$ package and can not be used on its own. So how to convert TikZ to say PNG comfortably?

$$\TeX$$-guru Martin Scharrer comes to the rescue: he wrote the package standalone for exactly this use case. Based on his explanation on tex.SE I built a small bash script that does all the repetitive work for you. With one simple command, this

%p% \usetikzlibrary{arrows,automata,positioning}
\begin{tikzpicture}[shorten >=1pt,node distance=2cm,auto]
\node[state,initial]    (q_0)                {$q_0$};
\node[state,accepting]  (q_1) [right of=q_0] {$q_1$};

\path[->] (q_0) edge [bend left]  node {$a$} (q_1)
(q_1) edge [bend left]  node {$b$} (q_0);
\end{tikzpicture}

becomes this in a matter of seconds:

Get tikz2png on GitHub and enjoy!

1. Check out the awesome gallery of examples and the comprehensive manual.
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Brandon Sanderson: The Alloy of Law http://lmazy.verrech.net/2012/03/brandon-sanderson-the-alloy-of-law/ http://lmazy.verrech.net/2012/03/brandon-sanderson-the-alloy-of-law/#comments Mon, 26 Mar 2012 11:00:42 +0000 http://lmazy.verrech.net/?p=3641 Read more »

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 Story: Characters: World: Humor: Action:

The Alloy of Law is set in the world of the Mistborn trilogy, about 300 years after the original books. The heroes of that time have become figures of myth and religion. The area around the pre-industrial capital (formerly Luthadel) is fertile and wealthy, farther out in the Roughs live is like in our Wild West. This is where noble-blooded lawkeeper Wax has made it his job to hunt down criminals until personal tragedy prompts his return to the city. He tries to blend in the noble society and behave as he should but is soon intrigued by a series of seemingly impossible thefts. Instead of preparing his inevitable engagement properly he starts to investigate, supported by his friend and colleague Wayne who has come to visit in order to make sure Wax does not die in of boredom.

Alloy of Law is fast, fun and tragic, but most of all fast. Allomantic-Feruchemic gunfights are probably the most awesome, cinematic thing I have read in a while. They show how incredibly well-conceived Sanderson’s magic system is: it evolves and scales with ease. The story itself is a diverting piece in Sherlock Holmes style, nothing too deep. There is potential for follow-up stories, though, so we’ll see. The main characters are very well-developed considering the size of the book; Sanderson makes every word count1. Besides the abundance of action, verbal exchanges between Wax, Wayne and later Marasi provide most of the fun and make the book a light read despite several tragic scenes. As a fan of the series, I enjoyed the many (religious) references—fact distorted to myth by time—to the old heroes, in particular how their way of life evolved to outright schools of philosophy2.

That I recommend a Sanderson book is probably no surprise, me being a devoted fan of his. Go and read this book even if you have not read or did not like3 the trilogy, it is fun!

1. This book is short by Sanderson’s standards!
2. Personally, High Imperial cracked me up the most!
3. The most frequent complaint seems to be that the trilogy is too slow-paced; this is certainly not the case for Alloy of Law!
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Computer Science Stack Exchange Live! http://lmazy.verrech.net/2012/03/computer-science-stack-exchange-live/ http://lmazy.verrech.net/2012/03/computer-science-stack-exchange-live/#comments Sun, 25 Mar 2012 14:11:25 +0000 http://lmazy.verrech.net/?p=3916 Read more »

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cs.SE in nondescript beta style

Since my post in December, Computer Science Stack Exchange has gone through private beta and is now accessible for everybody. Head over to cs.stackexchange.com and take a look! We are waiting for your questions so do not hesitate to post anything you have always wanted to know in computer science1, be it theory, applied or even practical!

We also need more expertise: out off almost 190 questions sixteen have yet to receive a good answer. among those are one about equivalence of Büchi automata and linear μ-calculus and another about efficiently learning regular languages.

You might also want to check out our hottest questions, including why Quicksort is often considered the best sorting algorithm, encryption using NP-hard problems and connections between Gödel’s incompleteness theorem and the halting problem.

I am very excited about this site. One one hand, it gives me the opportunity to share my knowledge in computer science with a wide variety of people, and I like teaching. On the other hand, I get to learn a lot. Not only do people ask about things I know next to nothing about so I can learn from the answers, but there are also original concepts. My favorite is Patrick’s proposal of heap automata; I have spent several hours contemplating his question about their power and follow-up questions.

I hope to see you on cs.SE soon!

1. Mind the FAQ, though.
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New Plugin: Cite & List http://lmazy.verrech.net/2012/02/new-plugin-cite-list/ http://lmazy.verrech.net/2012/02/new-plugin-cite-list/#comments Thu, 23 Feb 2012 11:00:05 +0000 http://lmazy.verrech.net/?p=3474 Read more »

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A simple bibliography with some citations

Finally! I have needed—and wanted to build—this WordPress plugin for a long time, and now it is done. Because I am so bad at making up names, I called it Cite & List because that is what you can do with it: cite articles and list your publications. Both tasks are easily done with shortcodes; users of $$\LaTeX$$ will feel right at home. You can also have everything look exactly the way you want it to, thanks to the use of bib2tpl.

Head over to the plugin repository and have a try! I like how the plugin turned out; hopefully I will have ample opportunity of using it, that is get to writing more sciencey posts.

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New Version of bib2tpl http://lmazy.verrech.net/2012/02/new-version-of-bib2tpl/ http://lmazy.verrech.net/2012/02/new-version-of-bib2tpl/#comments Thu, 02 Feb 2012 11:00:54 +0000 http://lmazy.verrech.net/?p=3472 Read more »

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Last weekend, I published a new version of bib2tpl, a PHP class to convert BibTeX to anything I wrote a while ago. There certainly were some bumps to iron out; these are the major changes made:

• Entry filtering now works on all fields.
• Templates can contain multiple occurrences of group and entry subtemplates now.
• Condition tags can perform more detailed comparisons now.
• Improved control over entry ordering.
• Grouping tags are no longer necessary if grouping is turned off.
• It is now possible to reuse parsed BibTeX for multiple conversions.
• @entryid@ has been removed; use @entrykey@ instead, which is now guaranteed to be unique.

You can find a more complete list of changes here, and more information on bib2tpl here.

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