Martin Geisler Online

We’re starting again at University of Aarhus: new exciting courses, new books and new lectures…

Uha, det er alt for tidligt at starte igen. Tillykke med de flotte karakterer. Godt gået. Skulle jo også lige prøve det her wiki halløj. -JanusTøndering

Mange tak! Jeg er helt enig — vi starter alt for tidligt! Jeg kunne godt bruge en ferie på en uge eller to. Men på den anden side, så må vi jo også se at få noget ud af alle de fine bøger vi har købt, de skulle jo nødig gå til spilde :-)

I’ve now had my final exam, this time in DAIMI:dArkOS. And I did it again, I got the grade 13… I must say that the grade surprised me this time, I would have expected to get a 10, perhaps 11, for I didn’t do anything exceptional. Sure, I delivered a good performance, I covered a lot of stuff—they told me afterwards that I talked very fast—and was able to answer most of their questions or at least I was able to say something intelligent when asked.

But I also got some questions that I couldn’t answer, so I tried to move the subject over to something else and then answer that instead… I didn’t go into much detail with some of my answers, I described how the solution worked and discussed the pros and cons, but I didn’t work it through in all detail. But apparently that didn’t matter as much as I though :-)

So now I’ll be relaxing until we begin again this Monday. I’ve already bought the books we’ll be using: the four books cost just over 2,000 Danish Kroner, that’s about 250 USD! But they’re all hardcover editions and look very professional, so I don’t mind paying for them.

Christmas is over, so it’s time to remove the red snowy background from GimpsterDotCom. But instead of using the normal blue color, I’m trying something new: a changing background color!

Each page start out with a blue background, but as people visit the page it slowly turns turquoise, green, yellow, red, purple and finally blue again. In other words, the color moves through the color-circle every time the page receives 360 hits. Funky isn’t it? :-)

To make it easy to change the color I made this little function to convert from the HSB (hue, saturation, brightness) color space to RGB (red, green, blue) which is what browsers understand:

function hsb2rgb($hue, $saturation, $brightness) {
    /* 0: minimum, +: rising, -: falling, 1: maximum. */
    $map = array(0 => array('1', '+', '0'),
                 1 => array('-', '1', '0'),
                 2 => array('0', '1', '+'),
                 3 => array('0', '-', '1'),
                 4 => array('+', '0', '1'),
                 5 => array('1', '0', '-'));
    /* Clip hue at 360: */
    $hue = $hue % 360;
    $i = floor($hue/60);
    $rgb = array();
    $min = 255 * $brightness/100 * (100-$saturation)/100;
    $max = 255 * $brightness/100;
    for ($color = 0; $color < 3; $color++) {
        switch($map[$i][$color]) {
        case ‘0′:
            $rgb[$color] = $min;
            break;
        case ‘1′:
            $rgb[$color] = $max;
            break;
        case ‘+’:
            $rgb[$color] = $min + ($hue % 60)/60 * ($max - $min);
            break;
        case ‘-’:
            $rgb[$color] = $max - ($hue % 60)/60 * ($max - $min);
            break;
        }
    }
    return $rgb;
}

I’ve figured out the conversion by looking at the sliders in the Gimp, so it could be wrong. Please correct it if you find a mistake… Credits go to DAIMI:~aveng (Lars Petersen) who got me started with this idea after showing me his nice PHP Imaging Lib.

Yesterday went perfectly, first the exam and then the birthday. I woke up a little past 8:00 when the construction workers started their machines just 15 metres from my window. They’re busy building a bunch of new houses in two stories.

I got some breakfast and then Camilla came by to say “Happy Birthday” and wish me luck with my exam. We’re all having our exams right now, she has just had a four hour long written exam in anatomy. She had to learn the names and functions of a huge number of muscles, and she had to learn it by heart. I’m glad that we’re allowed to bring our books with us to our exams…

I went to the University of Aarhus | http://www.au.dk/] at around 11:00 and thought that I came a couple of hours early. We don’t know the exact time of our exams, we only know what number we are on that day. If people don’t show up, then everybody is moved to an earlier time, so you have to come a couple of hours early to be on the safe side. It was my turn at 12:30.

I got BetaExamQuestions#q15] titled “Using Relational Database Systems in Object-Oriented Programs”. It’s a really good questions because there’s a lot to be said about it. I started with E/R diagrams and explained how these are mapped into relations which in turn can be made into CREATE TABLE statements in SQL.

After that was explained, I moved on to the impedance mismatch problem, that it the problem that our programming languages cannot work with relations natively, and that our (relational) databases cannot work with objects, records and other constructs like those natively. Object-oriented databases solves this by being able to handle objects with complex attributes, but I have yet to see a demonstration of such a database, so far I’ve only read about them in our database book.

I finished off by describing how we use databases from our programs, despite of the impedance mismatch problem. I talked about using embedded SQL and using a call-level interface. When I was done talking I was asked some extra questions so that they could see if I was just being lucky… They asked about all sorts of stuff like “What is a prototypical concept?” and “What is the block structure used for in BETA?”. I answered these questions as well and they decided to let me go while they talked about my grade.

A couple of minutes later Mads Torgersen came out with a big smile and told me that I got the grade 13! Of course I also smiled big when I heard this! I told him that this was probably the best birthday present I could have gotten and he agreed. I went home after having seen that Peter from my class had gotten a 10, which is also a very impressing grade.

When I got home to Skejbygård]] everybody was buzzing around: Martin hurried to raise the flag when he saw me and [Camilla, [Torben, and [Jesper were baking a surprise-cake that they didn’t want me to see. After I had told them the good news about my exam, I took a bath to get rid of the sweat from my bike ride back from Uni. They gave me the cake and a present while singing ”I dag er det Martins fødselsdag” (the Danish variant of ”Happy Birthday”), it was very sweet.

The present was IMDB:Shaft (2000) with Samuel L. Jackson. I haven’t seen the movie yet but I’m looking forward to it. The cake was good and so was the mood. Half an hour later my dad, my mom, and my younger [brother arrived from Aalborg.

They also brought me presents: a nice sweater, the movie IMDB:Artificial Intelligence: AI (2001) by Steven Spielberg, a CK One perfume, and more. My grandparents have sent me money so that I can go out and find something I like. My mom had also made a really good birthday cake, just like the one on the image at the top-right corner. We went out for dinner and then the family returned to Aalborg again a little earlier than 22:00.

So, all in all a perfect day: a perfect exam and a great birthday celebration afterwards. Thanks to everybody for making it so! -Martin Geisler

It’s my birthday today, I am now 21 years old! I also have my second exam today, it’s in DAIMI:dPaSS.

Happy Birthday then! Now I finally came by your homepage and tried to edit something by putting my little personal comment on your page. Neat work by the way… -Lars Lykke.