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Artifastring 2.0

After over a year of development, I have released Artifastring 2.0. This includes higher-quality output, an incredible amount of optimizations (up to 100x realtime), and now has multiple distinct instrument sounds: 5 different violins, 2 viola, and 3 cellos.

Most of the speed improvements are thanks to the Eigen C++ template library for linear algebra. In particular, this enabled me to easily write SIMD code rather than using floats.

Other bits of interest are the realtime OSC server and an interface for the Control (OSC) app. Users with iOS or Android tablets can control the physical modelling with their fingers! I'm hoping to have a video in a few days, although I still need to find somebody with a video camera. Before you get too excited, I should add that this is a proof-of-concept of the communication between tablet and computer; I haven't put any thought towards the actual GUI or ease of control. My focus is on finishing my thesis, so if anybody is interested in making better interfaces, go nuts!

There's sure to be rough edges left in this release. I'm trying to force myself to accept "the perfect is the enemy of the good". I'm having huge problems writing my thesis because whenever I write down what I've done, I think of possible flaws, which immediately prompts me to spend a week or two performing experiments which justify what I've done (or else demonstrate a real problem, in which case I spend another week or two changing even more!).

With that in mind, I expect a 2.2 release to happen within the next month or two. Of course, if more people test the 2.0 version and report problems, I'll have more confidence (and more motivation!) to get the 2.2 release out there.

Ubuntu ssh agent admitted failure

Ubuntu 10.04 LTS has a serious bug in ssh/ssh-agent/something which causes it to fail to log in to a system even if you have your ssh identies set up. This caused me an hour of panic before I found a workaround. I'm putting it here in case somebody else has the same problem and google finds this for them. (tl;dr: use )

I swap between two laptops and a desktop regularly. I have a shared dotfiles git repository, so my normal settings are fine -- but that won't work for stuff like email passwords, or even email. My current setup is to use an sd card for personal stuff. (yes, my stuff is in an encrypted loop-back partition on that card; I'm not crazy!)

A few days ago (just after returning to Glasgow), I started having read errors on the card. This was particularly sucky because although I'd bought a new 16gb card while in Vancouver, I hadn't gotten around to carrying that new card, so I was using my old 8gb card. I was planning on doing it "soon", but I definitely started to kick myself for not getting it set up sooner.

That said, it was only about 24 hours since I'd made a backup of the sd card anyway, and there hadn't been any truly important emails in that time. (I know the story should go "... but I didn't mind, because I'm using my brother's tarsnap backup service", but it was actually about 3 days since I'd backed up in tarsnap)

Fortunately, when I put the card in a different laptop, it read it just fine. I copied stuff over, checked that things seemed ok, and then started using the new card regularly. Everything seemed fine for a day or two, when I discovered that I couldn't log in to various servers. At this point, I turned to tarsnap to get a backup of my ssh directory, thinking that I'd gotten some freaky bitrot in my private key but nowhere else. No joy.

But wait, it gets worse! Take a look at this:

gperciva@gperciva-desktop:~$ ssh -v
OpenSSH_5.3p1 Debian-3ubuntu7, OpenSSL 0.9.8k 25 Mar 2009
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Connecting to [] port 22.
debug1: Offering public key: /home/gperciva/.ssh/id_dsa
debug1: Server accepts key: pkalg ssh-dss blen 817
Agent admitted failure to sign using the key.

LOLwut? Server accepts key, agent admitted failure to sign in using the key?!

After a bit of stumbling around, I found a ssh bug report from 2008 in the ubuntu database. Apparently you can work around it by setting SSH_AUTH_SOCK=0. You can also do some weird stuff with something called "seahorse", but I think I'll just export the variable.

Vampire Rabbit

The is the story of the Vampire Rabbit, and other bits and pieces from my European vacation from May 2 to 23. Yes, this is a bit overdue.

Overall, the timing of the first half was unfortunate -- I received the reviewer's comments about my Vivi paper just before leaving on the ferry. This meant that I spent the nights (after my traveling companion had fallen asleep) making typographical corrections, hunting up more references, and rewriting paragraphs to avoid misunderstandings. Now, there's a long Percival tradition of doing academic work while on vacation... but I had hoped that I'd have another 2-5 years before I fully embraced that life.

Processing the photos took a lot longer than I was expecting, and even then, there's still a lot of mistakes in them. Mispellings (I had at least two different ways of spelling "Ben Nevis"!), typos, wrong words, etc. But I've already spent far too long playing with these, so I'm reminding myself that "the perfect is the enemy of the good" and moving on. I'll only make a few additional comments to the photos.



Glasgow Edinburgh Highlands Newcastle and North sea (not scotland, but it fits in this section)

The trip began in Glasgow; my friend arrived from Vancouver. I only got lost once while looking for the airport bus to go out and get her, but I'd budgeted sufficient "buffer time" so that I wasn't late. The idea was that we'd spend a few days in an English-speaking country while she got over jetlag.

We began by walking all over Glasgow (particularly the West End, where Hogwarts is). Lest anybody doubt that I know how to show a girl a good time, the necropolis was a big hit. Direct quote: "This is so cool!".

Next day we went to Edinburgh, saw the castle, climbed Arthur's Peak, etc. On the way back to the train station, I wanted to find a washroom, and we ended up in the Scottish parliament debate chamber. True story! I saw a sign for the washroom, so we went into the building, and then security guards kept on noticing that I was looking around and seemed a bit lost, and they all said "aye, go on around the corner / up the stairs / through the doors", and there we were.

Driving tour of the Highlands; from Stirling to Fort Williams to Oban to Stirling again. Saw hills, ocean, sheep.

Final day in Glasgow: sort out any last-minute stuff for the rest of the trip. I bought a new travel shaver because my current one had really dull blades; new shaver was £37 while replacement blades were £44. Economy: 1, environment: 0? We also saw a junior (12-17 years old?) chamber music concert. Intonation was better than we expected, but dynamics and range of expression were worse.

Then we took the train to Newcastle-upon-Tyne. Saw the VAMPIRE RABBIT. Took the DHS overnight ferry to Amsterdam; an unexpectedly swanky trip. Highly recommended! It was much better than taking an airplane for 2 hours (plus all the travel to/from airport, security, waiting at gates, etc).



Amsterdam city pictures Amsterdam monuments Kukenhof flower market Leiden Amsterdam zoo

Amsterdam, city of bicycles. Deservedly famous for a huge fraction of the population of the population cycling as their main form of transportation. Also infamously famous for their red light district, which my travelling companion insisted on us visiting. (also infamously famous for marijuana, but since we've from Vancouver that wasn't particularly notable)

We spent an hour trying to find the red light district. As we were nearing giving up, we found a McDonalds and Burger King right next to each other, with red neon signs. We saw the red lights! ... ok, that wasn't the real place, but I was starting to doubt that it really existed. We saw five "chinese message" stores. They honestly did have massage chairs, and in one store there were people doing stuff with somebody's feet... but I really cannot believe that Amsterdam has such a huge market for chinese massages that it makes economic sense to have so many stores in such a small area. I suspected that "chinese massage" was a euphamism, but my companion insisted that she should be seeing "women in windows" with red lights.

After once again checking our two maps, cross-referencing them with a printed guide-book, checking the compass, and walking another 15 minutes, we found the red light district. This time, there was no doubt. It was about 9.30, so getting dark, by the way.

There really were red lights. I'd thought that "red light district" was just a phrase, but no -- there were individual "store fronts", lit with a red neon florescent bulb above the door and window. And in the window (actually, often the door), was a woman in "underwear". Often shaking or grinding, sometimes tapping the door to attract attention. It was... well, the first word that comes to mind is "tacky". Certainly not sexy!

That said, there was one "store front" which attracted my attention -- it did not have a woman cavorting about. Instead, there was a blond woman sitting on a bed, wearing glases, and reading a book. I'm fairly certain that the glasses were fake and the "intellectual" facade was a sham -- but at least somebody was pretending to be classy. And no, I didn't see any women with cat ears. Now *that* would have gotten my attention!

Note that we didn't make an extensive tour. We passed about half a dozen windows on our way into the central red light district, and then we saw a group of seniors in a tour group. We followed them for a bit; this group was circling a big old chuch smack in the middle of the red light district. My travelling companion thought that it really was a church tour group, but I pointed out that if they were honestly there to see the church, they'd have gone in the daylight, not at night. I mean, there were red lights just opposite the street from the chrurch, clearly visible from where they were. After circling the church, we stopped stalking the senior's travel group, and walked back to our hotel. We passed another half dozen windows along the way. No, we didn't stop for any of the live sex shows.

All in all, it was more weird than anything else. I didn't feel unsafe -- granted we left the area before 10pm, but the whole place still felt quite regulated and well-policed. And I certainly approve of having a safe place for this kind of thing! But it's not quite my scene, just like a football match isn't my scene. (I'm sure that the Amsterdam red light district is much safer than a British football match, though!)

The next day we saw a bunch of museums, and stopped for dinner at a "bergermeester", where I had a "meester biefburger" with "dragonmayo". It was absolutely gigantic (even by North American standards!), and I wasn't certain if I would eat it or if it would eat me.

Went to Kukenhof, saw flowers. Not being female, that's about all I can say about the place. :) After that, we went to the Concertgebouw. Saw a string quartet, not impressed. They played Haydn like Haydn (clean, together, careful, fussy, uninspired). The played Beethoven like Haydn. They played Debussy like Beethoven (some expression, moderate rubato, taking some risks, not always together but that's ok). No visible communication between the players; I suspect the Haydn and Beethoven was really together because they'd played it a lot and knew exactly what everybody was going to do.

Saw the zoo. Protip: reserve a whole day. We could only spend the morning there due to train ticket reservations, and regretted it.



Brussels city Brussels monuments Bruges Ghent Brussels museums Antwerp

Brussels wasn't as nice as Amsterdam. It's famous for fries (with mayonaise), but the two or three places we tried fries weren't particularly special. I mean, they were better than McDonalds fries, but that doesn't exactly say much.

Saw the Musical Instrument Museum. That was neat, and they even had a bunch of old electronic instruments in the basement! That was a very nice touch.

Really fancy churches. Protip: if you want to see art, don't bother with museums or galleries; just wander into a nearby church. Doesn't have to be a big cathedral; they all have fancy artwork.

We did a bunch of short trips to surrounding towns/villages/cities.



Paris city Paris monuments Paris museums Paris cemeteries

We were met at the train station by one of the LilyPond developers. He very kindly showed us around the town, translated, and gave us the "inside view" of the city! We got plenty of exercise walking around Paris.

We met with other LilyPond developers (plus some of their girlfriends -- that is, the girlfriends of some LilyPond developers. I haven't heard of any of them having more than one girlfriend!). It was really neat "putting faces to the names".

In addition to seeing the big sites, we visited a cemetery. I really liked the cemeteries in France when I visited in 1997, so I insisted that we go to one this time. Not for any kind of macabre reason, or any kind of "omg this famous person is buried here" reason -- I just like the fancy graves as pieces of scuplture/architecture.

South England


Dover Miscellaneous pictures from driving around Rye Steyning Amberley Swanage Corfe castle London

We met up with a friend and he drove us around southern England, starting from the ferry to Dover. We stopped to admire a few extremely picturesque villages and wild ponies, then arrived at the Dorsets area.

In the morning we saw the really cool Durdle door, then continued driving around, ending up at London for the night. In the morning, we briefly saw the really big tourist stuff (Buckingham palace, Westminister Abbey, parliament buildings, big ben, etc).

Returning to Glasgow was a pain. I dropped off my companion at Heathrow at 14:30, and then took the underground back to London Euston -- only to discover that the train had been cancelled due to high winds in the Scottish Borders area! Instead, I was to take a train up to Edinburgh (from King's Cross), then get a train from Edinburgh to Glasgow. But halfway along that trip, we were told that the train would end in Newcastle, and we should wait for the next train (which would be continuing up to Edinbrugh).

All in all, I only got back to my flat at midnight. It normally takes about 5 hours to go from London to Glasgow, not 11.5 hours! But I arrived eventually, exhausted but happy.

Tentative plan for next year: Berlin, Zurich, Vienna, Prague.