Audio books – first impression

A few weeks ago, I have heard about audio books and their popularity. For me the idea seems somewhat strange. I’ve been used to reading a book for ages and, at first, I haven’t seen any reasons for giving it a try. Most of books were “designed” for paper medium, so putting it in sound may give strange results. For example, some philosophical disputes require more time to think then trivial conversations. Because the reader usually recite with constant speed, listener have the same amount of time to process text regardless its content.

On the other hand, I love to listen some kinds of radio broadcast services. My favourite ones are BBC programmes. So maybe other voice pieces could also be interesting. Anyway, Having little to lose1 and a lot to gain2, I decided to give it a whirl.


Happily, Polish e-shops with audio books already exist. Despite offering only a small subset of books, I found one that I would like to read. The audio books are available as simple MP3 files. It was a pleasant surprise for me, because I suppose to have them in semi-functional format with DRM. Within usage of my bank account I was able to download them soon after after making a transfer.


Thanks to MP3 format, I copied audio book into my portable player. My first reaction after pressing “play” was “It’s different”. Listening a book is like going to the same place at nights. Trees, buildings, sites etc. are the same, but the general impression is other. The same is with audio books. The voice emphasise things which reader could easily miss and vice verse.


If you are still wondering whether audio books are worth hearing, you should definitely try them. They are especially handy when conducting or just waiting for someone. Within them, anyone could increase the number of read/heard books without too much effort.

  1. time + a few $ [back]
  2. find a new interesting thing [back]
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Debugging printing – CUPS

Some time ago I noticed that printing works somewhat strange on my desktop. It ran smoothly in most of the cases, but rarely it refuse to produce output. The really weird thing is that I didn’t know why it behaved in such a strange manner. As it is stated Murphy’s laws, it seem to fail when I was in a time-pressure situations. “Luckily”, One day, when my printer produced an error instead of doing its job, I had a time to solve the problem.

Analysis – user part

First of all, I needed to work out what is the real problem. I tried printing a few different documents. I selected those problematic and checked whether they are printable with other programs or configuration. The basic rules are:

  1. Repeatability and reproducibility – in what kind of situation does problem occur? Am I able to reproduce errors within doing the same steps? Does the problem repeat while using certain applications or it is document/configuration specific?
  2. Isolation – what kind of programs are involved? Pinpoint all of the programs and configuration files that could cause the problem.

My answers to this questions:

  1. Repeatability and reproducibility – the problem seems to be document specific. I found that it occur only within a small number of PDF and ps files.
  2. Isolation – printing program related to CUPS such as ghostscript, pnm2ppa, foomatic and CUPS itself.

Analysis – debugging

At first I looked up for logs (“/var/log/cups/error_log”). It wasn’t useful at all, however It suggested turning on the debugging mode. So I look into CUPS config (“/etc/cups/cupsd.conf”) and changed LogLevel to debug.
[code lang="bash"]
#LogLevel info
LogLevel debug
I tried printing one of those baffling documents. I looked at errors and saw:
[code lang="bash"]
D [17/Apr/2007:22:15:56 +0200] [Job 151] GPL Ghostscript 8.54 (2006-05-17)
D [17/Apr/2007:22:15:56 +0200] [Job 151] Copyright (C) 2006 artofcode LLC, Benicia, CA. All rights reserved.
D [17/Apr/2007:22:15:56 +0200] [Job 151] This software comes with NO WARRANTY: see the file PUBLIC for details.
D [17/Apr/2007:22:15:56 +0200] [Job 151]
D [17/Apr/2007:22:15:56 +0200] [Job 151] Closing renderer
D [17/Apr/2007:22:15:56 +0200] [Job 151] Error: /VMerror in --stringwidth--
So it is definitely a ghostscript error. I googled VMerror and found that it is a postscript error which means that my RIP (ghostscript in this case) doesn’t have enough memory. Because I have a lot of free RAM, it is probably a bug of ghostcript.


I simple searched for ghostscript alternatives in the portrage(“eix ghostscript”). I decided to switch from “ghostscript-GPL” to “ghostscript-esp” so I entered:
[code lang="bash"]
emerge --unmerge app-text/ghostscript-GPL
emerge app-text/ghostscript-esp
/etc/init.d/cups restart # restarting cups service
After these steps printing services work properly.

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Strange error

I encountered a strange error while I was using subversion. I was checking out some of the programs sources while I got a message:

Fetching external item into 'koffice/kdgantt'
svn: PROPFIND request failed on '/home/kde/trunk/KDE/kdepim/kdgantt'
svn: PROPFIND of '/home/kde/trunk/KDE/kdepim/kdgantt': SSL negotiation failed: SSL disabled due to library version mismatch (

As I had correctly installed subversion and openssl, I guessed that the linkage is the problem. That kind of problems should be removed by running revdep-rebuild. This time revdep didn’t help, so I re-emerge both programs manually. After that, svn worked as usual. The strange behaviour seems to be an issue of portrage’s ebuild.

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Olympiad in Informatics

I’ve just returned1 from the final stage of Olympiad in Informatics(OI). I scored 14th place2 which gave me a title of laureate. It’s a really high position, because it is the hardest algorithm competition at a high school level. This post is a brief summary of my thoughts about it.


Although that the Polish education system has its drawbacks, there is a definitely positive thing. The Olympiads. In fact it’s hard to translate this term into English. By “Olympiad” I mean a national competitions from different subjects for a high school students. In contrast to normal competitions, they are organised by the most prestigious Universities. This series of competitions require far more knowledge and skills than is normally taught at school. It’s a kind of motivation for students to learn more than it’s in official program.


OI is slightly different than the rest of the Olympiads. It consist mainly of algorithm problems. The objective is simple, write a program that will calculate the answer for given input within time and memory limits. For example, for a given graph find the route that has length exactly k. Judging is totally automatic. A score is evaluated based on how many of the tests your program has passed correctly. Unlikely the other algorithm competitions, the most important aspect is thinking rather than coding. The contest is divided into two sessions, each of it lasts 5 hours and include only 2-3 problems, so finding an optimal solution is the crucial part.


The another reason why OI stands out is a location of the finals. Most of the Olympiads choose an academic city, while the OI 3rd stage is in a awesome coast resort – Sopot. Thanks to one of the sponsors, Combidata, we were accommodated in a training centre. It’s situated near the sea. Although in spring it’s too cold to swim, it’s truly pleasure to walk on the sand.


What’s really important is the people. It’s one of my few possibilities to talk about technical issues. Wanting a short discussion about various garbage collectors? Or a short talk about open source licensing? During the finals we have opportunity to meet/talk about almost all of the programming topics.

To give an image what’s sort of people are there, a short statistics:

Popular OS: linux flavour, mostly gentoo
Popular languages: C++ + a wide range of interpreted ones
Favourite (future) employer: Google
Other fields of interest: mathematics, physic + very odd one


At this competition I learned that I don’t exist ;-). I had a starting number 404 (HTTP not exist).


To be honest, I dreamed about achieving a better result. I’ve made one genuinely silly mistake. I coded a constant value with one more zero than it was written in a problem set. It cost me a lot of points. On the other hand, I performed well enough to be almost on the top.


Preparation for OI took me long hours and many months of hard work, but it definitely worth it. Not only I learned many algorithms, but also I learned how to solve problems. It widen my mind, show new possibilities, give me a chance to meet new friends, etc. Although this contest concentrate on algorithm, it’s a good starting point to discover other branches of informatics.

  1. In fact a week ago. I published the post with a delay. [back]
  2. Results of Olympiad in Informatics 2007 [back]
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