Looking for an excuse to try out Google AppEngine, and encouraged by someone on StackOverflow looking for a free web service to convert between currencies at historical dates, I built the Historical currency converter web service. Using a very simple RESTfull API, you can convert between all currencies on the ECB’s list, using exchange rates that date back to January 1999.
Historical currency converter web service
Feb 16th, 2010 by Wim
Questioner or answerer?
Jan 7th, 2010 by Wim
Yesterday on StackOverflow, I came across one of those users that kept asking questions, but didn’t really seem to understand much of the responses. Looking at his profile, it turned out he had asked over a hundred questions, but contributed less than ten answers. I won’t be tempted to start about his capabilities of actually answering any SO questions (although his understanding of other’s answers to his own questions, except when he was able to copy-paste someone’s source code, also didn’t seem to be that great), but it did get me thinking about what a ‘common’ ratio of questions versus answers would be for other SO users (personally, I’m at 1/85 right now). Of course, that triggered my data-analysis and graphing gene…
Panoramic images with Hugin
Dec 21st, 2009 by Wim
StackOverflow user diversity
Nov 8th, 2009 by Wim
I’ve been wondering what the diversity of knowledge of StackOverflow users would be like. It seemed like an interesting research idea to see how many people have responded only to questions in a very narrow field, and how many others have broader knowledge and can contribute useful answers in more diverse fields. Apparently, there is even supposed to be a badge for that (the Generalist badge), but it didn’t get implemented yet.
It’s easy to do this using tags: some sort of clustering should be applied according to how often each pair of tags shows up at the same question (a user that knows both ASP and ASP.net shouldn’t be considered a ‘diverse’ person, so this should be factored out first), next we can count in how many different clusters that this user has contributed a good answer.
Dwengo Boards now selling!
Sep 1st, 2009 by Wim
Our first 100 Dwengo boards just arrived from the plant in China. Luckily, in contrast to the first prototype, all the LEDs are now soldered on the right way.
TOP500 list by interconnect
Aug 26th, 2009 by Wim
While attending a Hot Interconnects talk on supercomputing, I got the following idea. The TOP500 site provides graphs of the number of systems and total performance per interconnect family, which shows an approximate measure of the popularity of the different interconnects. But how do they affect the performance of an individual system? Clearly, a high-performance interconnect should result in higher efficiency than a commodity one. But by how much? And which systems would use what type of interconnect?
Tokina 11-16mm f/2.8 wide-angle lens
Jan 10th, 2009 by Wim
… or how to make a small space look huge.
I couldn’t resist, and bought another lens. This time a real wide-angle lens, the Tokina AF 11-16mm f/2.8 AT-X Pro DX. Yes, it’s a zoom lens, and on paper the range fitted nicely to my Tamron 17-50mm f/2.8. But the difference between 11 and 16mm turned out to be so tiny (and the image quality so good that cropping an 11mm image down to 16mm would be more than adequate), that I might as well have gotten a prime 11mm one. But still, a very nice lens this is!
Practical Compressor Test
Jul 5th, 2004 by Wim
Welcome to the ‘Practical Compressor Test’. Unlike some other compressor comparison sites, I won’t be looking for a compressor offering for the last bit of compression. Instead I’ll try to find the most practical compressor out there. This means compression and decompression times are taken into account, so PAQAR and the like, which can achieve very good compression at the expense of insanely long run times (several hours on this benchmark!) are not considered.
Instead I’ll be focusing on very well known, established compressors that are easily obtained (I only use precompiled packages and won’t build from source) and have reasonable run times. Also I won’t try every combination of compression options but limit the test to one general option (-1 to -9 for gzip and bzip2, -m1 to -m5 for RAR, …).