"In het verleden behaalde resultaten bieden geen garanties voor de toekomst"

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About this blog

These are the ramblings of Matthijs Kooijman, concerning the software he hacks on, hobbies he has and occasionally his personal life.

Most content on this site is licensed under the WTFPL, version 2 (details).

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Planning at ORTEC

Right now, I'm in Gouda in a bus heading towards ORTEC, a company that works with planning software and algorithms. Today they organise a in-house day. Together with a number of math students of Study Association Abacus we are going to work on a case titled "Restrictions within the Dijkstra algorithm".

So far we've been underway for 3 hours to get here, currently we're bouncing around in this bus, since the driver seemingly wants to catch up his delay. We're off to a good start, since as soon as we get there, we'll start with lunch (probably after a short boring intro talk). Read on for a "live" report :-)

See more ...

5 comments -:- permalink -:- 17:36
Educational market and Laserquest

Today was the "educational market" (Onderwijsmarkt), organised by Inter-Actief. Main attraction where the design projects, which had all made a (more or less) pretty poster presenting their project and findings.

Since we had been well-warned to take care of the poster well before today, we started work on it yesterday, since it was the first moment anyone had some free time since we decided we (Marijn and I) would stop postponing it last friday.

Making a poster

I had already made some preparations on monday in the train, mainly thinking about what should be on the poster and writing some text to put on there. I started yesterday morning (got up at 8 for this!) with actually putting together a poster with a few screenshots and the text I had written.

After some fighting with the vector drawing program [Inkscape], which we used since Marijn knew it pretty well, I had put together something really, really, ugly and unfinished. Being out of time, I bailed and left the thing to Marijn. He managed to turn it into a pretty decent poster with nice colours and lines and all.

Printing a poster

He gave it back to me, so I could take care of the printing (he had to work this morning). I spent an hour or so last night battling with the various svg, (e)ps and pdf files, which turned out to contain a subtle error somewhere. This made all my attempts to properly chop up the A0 poster in 8 A3 pages fail (we were already too late to let it print in A0). After doing some more CDP homework, I gave up on it and went to bed. Since I did not expect the printing of the poster to work in one try, I slept less than four hours and got up early. Pling Poster

This morning was spent trying various file formats, drawing programs and printer settings at the print shop (The guy there always lets me fiddle around myself) and at first gave me a poster (that is, in 8 A3 pieces) in which all the images were black and white. Being happy that I had got at least something, I returned to Inter-Actief to see if the adobe suite could help me out.

After some fiddling around with Illustrator, I managed to convince it to print my poster on 8 A3 sheets. Using the Adobe pdf printer, I turned this into a nice, self-contained pdf to print at the print shop. Worked out pretty well, this is something we can do more often at Inter-Actief, since we currently use Photoshop to split a poster into four png images to be printed on A3 paper.

Presenting a poster

The presentation of the poster was pretty informal, everybody walked into and out of the room and looked around, playing our game and looking at our poster. We also got an "official" visit from the jury, that had to select the best poster of the day.

Later, at the drink afterwards, the winner of the best poster award was announced. After some honourful mentions, they announced our poster to be the best one. Pretty nifty, since it earned me (the other group members were already gone) an applepie. Pretty weird too, since the poster was really a not very thought through bunch of information on 8 poorly taped together A3 sheets. Ah well, apparently I had written some interesting things by accident and Marijn did a good job at layouting it.


After such a night of little sleep and an intensive day, it was time to get to bed early and sleep a lot. So, I went over to Inter-Actief at 1930 to go Laserquesting. I had done it one time before and really liked it and since I had no other appointments this time (as I had the last two times), I decided to go anyway. Also, the last time only three people wanted to go and it was canceled, didn't want to break the mood this time ;-)

After three immensely intensive games of laserquest (my muscles will probably be aching tommorrow), I am now really ready to go to bed and sleep a lot. I'll see about that class tomorrow morning (1040), might not go there if I'm still tired then.

So, time for bed. Goodnight.

0 comments -:- permalink -:- 17:35
Moving out, Moving in

This week is the last week that I'm officialy living in my own room at the Calslaan, I've been busy moving out over the last few weeks. The room is nearly empty now, I've spent my last friday removing the planks from the walls and replacing the plugs by fwall filler (Unfortunately, the plugs did a pretty decent job at staying put, so there are still some remains of them in the wall...).

It's probably no surprise that I'm moving in with Brenda, at her place in Twek. Since she got here own place there over a year ago, I've been "visiting" her more often and often. Since I'm now spending most of my (free) time there, it makes sense to make that official as well. It doesn't feel like that big a step (since the living together part happened gradually), but actually moving in together is still a next step of commitment (which I am happy to take).

We finished most of the moving stuff part a few weeks back, just before I started my internship at Recore Systems. This is the one-but-last part of my studies, after I finish my internship in august, I have only my final thesis remaining (though that's gonna take at least 6 more months). So, the end is in sight, but still not so near :-)

1 comment -:- permalink -:- 15:45
/ Blog / Uni

I've finished both of my exams for this quarter: Signals & Transformations and Circuit Analysis. The first is a master's course on mathematical models of (electrical) signals and performing (theoretical) transformations on them, involving a lot of complex numbers. The second is performing analysis on simple electrical networks with resistors, capacitors and inductors. Not too hard to grasp, but juggling around with hands full of different resistor values tends to get messy after a while. Also, the last part of the course involves, you might guess, complex numbers! Both these exams went pretty well, probably 7+ (out of 10 marks).

No, I don't know what this means either...

During the circuit analysis I've learned that electrical engineers have nasty habits. They have the tendency to not conform to the standard mathematical conventions that the rest of the world does (this view might be a little biased, though ;-p). The best example of this is the way they write complex numbers. Some time back, a bunch of mathematicians agreed that there was need to calculate with the square root of -1 (Sqrt(-1)). While everybody agrees that this number is called i, they insist to call it j, since i conflicts with their symbol for electrical current. Anyway, I think I managed to do both exams without switching them, but I've been mixing them up all the time so far...

Besides these minor inconveniences my electrical engineering minor is starting out OK. Since I've already done Circuit Analysis, which I expected to be next quarter, this leaves only 15 ECTS in my minor. Since that is enough to fill two quarters (which was the original plan), I'll probably try to squeeze in instrumentation for embedded systems, a mandatory masters course, which should not cost too much time. Only problem is that it's given at the same time as another lab course, but I should be able to get away with that...

0 comments -:- permalink -:- 20:58
Summer 2006: Summary and highlights

Anyone that knows me just a little, will know that the emptyness on my blog this summer, has not been caused by a shortage of things to write about. Quite on the contrary: I've been doing so many things I could have written about, that it didn't leave any time to do the actual writing. By now, classes have begun again, so I won't be having too much time soon either. So, instead of full length posts about all the fun stuff, I'll do a one post summary. I might even make it short.

De Randmeren

So, where have I been this summer? I've been around, but most of the time somewhere in Harderwijk or Ermelo, at either one of my parents or at Brenda's. Most of my summer has been spent helping out at sailing school "De Randmeren" my father started this year. I've mainly been assisting with administrative tasks and boat rental, but also with giving sailing lessons. Since they have just started, I have been setting up most of their administration, both financial and other. I've even been working on an online customer administration system, but it has not been deployed yet (I'll leave that for the winter, together with a complete website redesign by Brenda). During one of these weeks, Tin came over from Enschede to help us out with the youth sailing lessons. Thanks, Tin!

Apart from making a few bucks by working there (though not much, since it is still a starting company), I've been getting a lot of experience, in various areas. The last two weeks I've been working there, I was my father's replacement, since he went on a vacation. Those weeks, I've been basically running the company, together with the other owner, Erik. Very useful experience.


Another major time sink during this summer was Exodus, an event by Evolution Events, for which I have been organising. I've mainly been busy with the various IT support tasks, which went well mostly (could have been better if I would have had some more time...). The event itself, at the end of august, was quite succesful. We have been receiving a lot of positive feedback from our participants and we are happy with how the event itself turned out. Best example of this was the saturday night dinner, which was served fully IC, so people continued playing not only over dinner, but even when doing the dishes!


Somewhere in between there I've been spending some time with Brenda. We have been away for a few days of camping, by bike! Brenda has done cycle vacations with her parents for years and has wanted to do so again together with me. This year, I've finally gathered enough courage and Brenda arranged me a decent bike (borrowed from her neighbours), so nothing stopped us anymore.

We've been cycling for 4 days, starting in Ermelo, going to Elburg, Wesepe (near Olst), Kootwijk (near Apeldoorn) and back to Ermelo, for a grand total of about 150 km. Pretty impressive distance, for me at least. We have been staying at nature campings (Small, cheap campings, having only bare sanitary), in a brand new hiking tent (only 2kg!) I gave Brenda for her birthday.

Other stuff

Furthermore, there is some other stuff I'd like to mention (and possibly write some more about in the future). Last week, I've been scourging the "boeldag", a yearly second hand market in Ermelo. Apart from some useful LARP stuff, I found an original NES, for free! I've tested it this week and it worked, at least somewhat. I do need to find/build a power adapter and some controllers, since I got it completely bare. I've also found the NES is a fairly simple machine, which makes it ideal for modding and hacking :-) Nice for the stack of nice-projects-when-I-have-some-time.

Ever since I've purchases my notebook, I have been looking for a name for it. Somewhere during this summer, I've finally named it "Xanthe", a name I came across a while back that stuck around. Now all I need is a catchy name for my blog (and a matching .nl domain name)...

Just last week, I've finally decided to do the embedded systems master here at twente. I've been through some trouble to participate in a few courses for which I didn't subscribe in time (ie, before the summer).

2 comments -:- permalink -:- 19:10
/ Blog / Uni
The voodoo has been done

This morning's CLP exam went pretty well. Despite the high voodoo-level of promela, the language used, the exam was easier than I expected. Now let's hope I did well enough.

As I was hanging around at Bas' place to chill and discuss the exam, we noticed something at Inter-Actief breaking (both nerding away on our respective laptops). Within 10 minutes we were on the site to see why our (Windows) domain controller had stopped responding. We discovered that it had decided that the windows update it had just installed required a reboot and just went ahead with rebooting. Rebooting that machine is a bad idea anyhow, since it takes more than 15 minutes, during which half of Inter-Actief becomes useless, ICT-wise. Better yet, it had managed to hang itself somewhere between shutdown and boot, so a reset was required. Go Windows!

Anyway, I'm off to Harderwijk now, sailing course tonight, and opening of my fathers new sailing school this weekend. Since I'm planning on becoming a sailing instructor there, that means plenty of sailing this weekend :-D

0 comments -:- permalink -:- 14:52
Miscellaneous stuff

This post is about a bunch of stuff that happened today (or has some relation to that stuff :-). I am currently waiting for the bus to take me back home, so perfect opportunity to write some things down. If only the sun would come back now... I will not write about last weekend's Symbols event, I am working on another, huge, post about that.

CDP exam

So, this morning was my CDP exam. I had not prepared too well, following only about half the classes (they weren't too good anyway...) and not making all of the homework exercises (meaning that even if I would make the exam flawless, I would only get about 8 out of 10 marks).

Still, I was planning on passing this course, so I teamed up with Bas, who also had to do the same exam (but didn't really follow the course at all this year). This turned out to be a good idea, since it prevented both of us from getting distracted too much. We made our base of operations at the Inter-Actief room, so we would have a printer to print some reference material (the exam was open book). This reminds me, I have to drop by there sometime this week to pay for the pages I printed....

Anyway, I found the exam this morning to be easier than expected, I actually had an answer to all of the questions. So, it seems I might have actually passed after all.

Stupid PIN codes

Anyway, after this exam I was planning to drop by the postal office to pick up my new bank card. Exactly two weeks ago, I was trying to pay for Laurens' birthday gift in a store and I realized I didn't remember my pin code anymore. Everybody forgets stuff sometimes (especially me), but knowing your own pin code is so natural, that it feels as if your mind is seriously broken if you don't remember it. Complete weirdness. Anyway, since I had a few vague ideas about my pin code before suddenly remembering the telephone number of Inter-Actief and mistaking it for my pin code, I got my card blocked.

Next day, I made a trip to the bank, who promised to give me a new pin code, since I still didn't remember it. Four days after forgetting it, I suddenly remembered my code again, but it was no use anymore. Anyway, I got my new pin code, but also some other letter from the bank for which I needed to identify myself to get it. Probably a new bankcard, though the guy said I would only get a new pin code. Ah well. Since I was away last weekend, I had to pick it up at the postal office.

Postal WLAN

So taking the bus to the postal office (expecting to have to drop by the bank too to activate the card), I realized there that it would not open for another half hour. But, there was sun and I had my laptop, so I would write some about Symbols for my blog.

I ended up yanking my laptop's on-board WLAN card into scan mode, to see if I could get an Internet connection and hang around on IRC. I found multiple unencrypted WLAN networks, of which one seemed particularly interesting. It's network ID was "default", which offered a good chance to a non-secured open Internet connection set up by someone not taking the effort of reading any manual or getting some clue.

It turned out that associating with the access point wasn't that hard. Just tell the SSID to wpa_supplicant and be on your way. On the other hand, getting a DHCP lease proved impossible. I suspected the network to be statically configured, so I fired up my favorite packet sniffer Ethereal and made it listen. I was hoping to get a few TCP packets that would allow me to guess the network range and gateway address. No such luck. I did receive a few DHCP DISCOVER packets, which turned out to be not all mine.

At first suspecting that someone else was also trying to get a DHCP lease, or probably just the PC that was supposed to be connected by this access point, I decided that the DHCP server was probably off or broken. That's when I noticed that the DHCP discover packets were not aimed at the access point, but actually originated from this access point. I didn't know why, but this AP was trying to get an IP address.

As kind as always I decided to boot my own DHCP server (it's always nice to run a real OS on your laptop) and give the poor AP an IP address. This actually turned out to work, so I was hoping to get some Internet connectivity soon. Pointing my web browser at the IP address I just gave to the AP gave me a nice login screen, for which my second try (admin/admin) worked. So, I could now easily reconfigure just about anything on this AP (which I didn't, because that would have been rude). It turned out this was just a access point and no router, that had it's LAN interface set to DHCP client. Probably the DHCP server on the LAN was unavailable (or the AP wasn't configured at all, perhaps) and for some reason it didn't just direct it's DHCP requests to the LAN interface, but also to the WLAN interface.

Anyway, since the LAN side of the AP was only configured by my DHCP server, I had no idea on how to actually reach the Internet from here. Also, the postal office opened, so I had played enough and got back to the useful stuff. I finally picked up my bank card (which was activated immediately, so no need to drop by the bank).

I was planning on dropping by Simon too at Saxion, to talk about last weekend's Symbols and the System we are going to develop. But since he was at home sick, I did some shopping and went home. Now (it's after dinner as I finish this post) it's time to do some learning for Thursday's CLP exam, again together with Bas. We already decided we would allow ourselves to do some coding on Claud-IA, the to-be-built user management system for Inter-Actief. But, first some CLP...

2 comments -:- permalink -:- 19:59
/ Blog / Uni
Spin & XSpin: formal verification

I'm following a course called "Concurrent and Distributed Programming" (CDP). It concerns programs that run at the same time in a multiprocessor, multiprogrammed or multiple device environment. The main part of the course is proving correctness of such programs. In layman's language: If multiple things happen at once (such as lots of cars driving on a crossing), how do you prevent certain things from happening together (cars driving in perpendicular directions) without the risk of waiting forever (always letting one direction first).

Pretty interesting stuff, actually. Quite a different mindset from normal programming. I've already had some experience with this in other courses (Operating Systems, Programming), but this is more formal and actually proves that algorithms are correct. Something I like :-)

The nasty side of it is that the classes are pretty chaotic. The teacher doesn't really do a good job at explaining the stuff. Add to that that a lot of her sheets (containing very formal, non-trivial to understand code) contain stupid errors and you get a pretty lousy class.

Anyway, I've been installing spin, the validation tool used for this course. I have yet to understand what it can do, though. For now, I was able to do the first (easy) assignment by clicking around in the graphical front-end, xspin. Both are pretty easy to install. Spin is written in C and needs a simple compilation, xspin is TCL/TK and works out right away (if you follow instructions).

The bigger challenge was to make a screenshot of the application showing the simple Promela model, the output and my name. After doing the necessary resizing and converting (I had to hand in the screenshot in PDF format...), I got it done. Let's hope the classes will improve a little and this might turn out to be a fine course.

3 comments -:- permalink -:- 20:50
/ Blog / Uni
Graph theory is nasty

I've been studying graph theory all night, mainly reading at first. Since I have only little time until my exam tomorrow afternoon, I don't have the time nor the concentration to fully comprehend and prove the correctness of all that I read (which I normally tend to do). Also, I have barely done any exercises, apart from a practice exam just now.

It's not hard given the appropriate definitions and theorems, but since they are not given and I do not know all of them by heart, we'll see what happens tomorrow. I'll try to remember some more definitions in the morning and hope they'll stick... First some sleep, though.

0 comments -:- permalink -:- 00:24
/ Blog / Uni

Now that (operating systems exam) was a piece of cake. Finished in 90 minutes, as one of the first. Had to do some guesswork, but I expect a decent mark on this.

Now, let's prepare some dinner and set off for a night of learning my Graph Theory (exam tomorrow afternoon).

0 comments -:- permalink -:- 16:25
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