First Brew

I remember Dad preparing a batch of homebrew in the evening then a lazy sunday spent bottling the 20 litres or so of beer. I have always wanted to brew over here in sweden but due to lack of linguistic knowledge, I have never found a place that I could pick up a plastic vat to ferment the beer. Until this afternoon. I went to Malmö and picked up a 25L vat with all the necessary equipment on my way to band practice.

As much fun as it was using it as a drum at practice, I brought it home tonight and using a Cooper's Pale Ale extract and a kilo of dexterous made my first brew. All ready to bottle over the weekend. I'll report back with photos and a flavour report.

Open Drums

I wanted to be able to record any ideas I had for drum beats quick and easily. This was much simpler that I expeced.

After getting OpenDrums, and installing a few graphics packages:

$ sudo apt-get install libsdl1.2-dev libsdl-image1.2-dev libsdl-mixer1.2-dev
$ make

It works like a charm, now to change the default sounds to something a little more realistic.

Canon Pixma MP270 driver in 64bit Ubuntu

Canon provides the 32bit drivers to the Pixma MP270, but not 64 bit driver. Instead of building them from source, just get the 32 bit drivers from canon's site.

In the packages directory there are 2 debs. All you need to do now is:

sudo dpkg -i --force-architecture ./cnijfilter-common_3.20-1_i386.deb
sudo dpkg -i --force-architecture ./cnijfilter-mp270series_3.20-1_i386.deb

And the printer should work :)

Ruby on rails 3 - rvm, bundle, eeeekk

Having a freshly loaded Ubuntu 10.04 on my main desktop (after checking it out for months on my laptop), I thought I'd get ruby on rails set up. After setting up Rails 2 with the minimum of fuss, I took the challenge of upgrading to Rails 3 (release candidate).

RVM is now an essential component of any rails environment, letting you change between rails version in an instant (Theoretically, but more on that soon).

Installing it was as simple as:
$ bash < <( curl http://rvm.beginrescueend.com/releases/rvm-install-head )

After installing all the necessary ubuntu packages

$ rvm install 1.9.2-rc2
$ rvm 1.9.2-rc2
$ gem install rails --pre

I can't seem to switch between rubies as I would like, but I'm sure I can solve this soon.

To start a new project we have to forget the rails 2 ways and start with:

$ rails new test_project

You should see the usual files (plus a few new ones) being created.

$ cd test_project
$ bundle install

This is where I had some problems with mysql. I had installed every possible mysql package but it stll wasn't working.

Using activeresource (3.0.0.rc)
Using bundler (1.0.0.rc.1)
Installing mysql (2.8.1) with native extensions /usr/local/lib/site_ruby/1.8/rubygems/installer.rb:483:in `build_extensions': ERROR: Failed to build gem native extension. (Gem::Installer::ExtensionBuildError)

/usr/bin/ruby1.8 extconf.rb
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lm... yes
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lz... yes
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lsocket... no
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lnsl... yes
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lmygcc... no
checking for mysql_query() in -lmysqlclient... no
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers. Check the mkmf.log file for more
details. You may need configuration options.

Provided configuration options:
--with-opt-dir
--without-opt-dir
--with-opt-include
--without-opt-include=${opt-dir}/include
--with-opt-lib
--without-opt-lib=${opt-dir}/lib
--with-make-prog
--without-make-prog
--srcdir=.
--curdir
--ruby=/usr/bin/ruby1.8
--with-mysql-config
--without-mysql-config
--with-mysql-dir
--without-mysql-dir
--with-mysql-include
--without-mysql-include=${mysql-dir}/include
--with-mysql-lib
--without-mysql-lib=${mysql-dir}/lib
--with-mysqlclientlib
--without-mysqlclientlib
--with-mlib
--without-mlib
--with-mysqlclientlib
--without-mysqlclientlib
--with-zlib
--without-zlib
--with-mysqlclientlib
--without-mysqlclientlib
--with-socketlib
--without-socketlib
--with-mysqlclientlib
--without-mysqlclientlib
--with-nsllib
--without-nsllib
--with-mysqlclientlib
--without-mysqlclientlib
--with-mygcclib
--without-mygcclib
--with-mysqlclientlib
--without-mysqlclientlib


Gem files will remain installed in /home/stumacd/RoR/projects/wiki/ruby/1.8/gems/mysql-2.8.1 for inspection.
Results logged to /home/stumacd/RoR/projects/wiki/ruby/1.8/gems/mysql-2.8.1/ext/mysql_api/gem_make.out
from /usr/local/lib/site_ruby/1.8/rubygems/installer.rb:446:in `each'
from /usr/local/lib/site_ruby/1.8/rubygems/installer.rb:446:in `build_extensions'
from /usr/local/lib/site_ruby/1.8/rubygems/installer.rb:198:in `install'
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0.rc.1/lib/bundler/source.rb:96:in `install'
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0.rc.1/lib/bundler/installer.rb:51:in `run'
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0.rc.1/lib/bundler/spec_set.rb:12:in `each'
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0.rc.1/lib/bundler/spec_set.rb:12:in `each'
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0.rc.1/lib/bundler/installer.rb:40:in `run'
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0.rc.1/lib/bundler/installer.rb:8:in `install'
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0.rc.1/lib/bundler/cli.rb:115:in `install'
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0.rc.1/lib/bundler/vendor/thor/task.rb:22:in `send'
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0.rc.1/lib/bundler/vendor/thor/task.rb:22:in `run'
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0.rc.1/lib/bundler/vendor/thor/invocation.rb:109
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0.rc.1/lib/bundler/vendor/thor/invocation.rb:116:in `call'
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0.rc.1/lib/bundler/vendor/thor/invocation.rb:116:in `invoke'
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0.rc.1/lib/bundler/vendor/thor.rb:161:in `start'
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0.rc.1/lib/bundler/vendor/thor/base.rb:379:in `start'
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0.rc.1/lib/bundler/vendor/thor.rb:140:in `start'
from /usr/lib/ruby/gems/1.8/gems/bundler-1.0.0.rc.1/bin/bundle:13
from /usr/bin/bundle:19:in `load'
from /usr/bin/bundle:19

The trick was to install it with the correct parameters (found by using $ which mysql)

$ gem install mysql -- --with-mysql-conf=/usr/bin/mysql --with-mysql-lib=/usr/lib/mysql

This allowed all the applicable gems to be installed.

And now with a:

$ rails server

WEBrick was up and running and http://localhost:3000 was showing the standard page. Gold dust :)

Decapus - 10 legged power supply

Having built guitar effects pedals for the last 10 years, I've progressed from battery power to requiring a power splitter for a decently powered DC adapter.

The overall plan is to put the power supply on the underside of the pedalboard, so I needed about 10 outputs and four to be longer than others.



It's a very simple design, but it really needs to work reliably and a minimum parts count was desireable.



So it's not that pretty, but it's rugged enough to sit on the bottom of the pedalboard without to any dramas.

Codility

I was reading a blog concerning how to hire new programmers. According to this blog, one of the classic mistakes some recruiters make is that they don't get the propsective candidate to write any code during the interview. This seems a bit odd, but I guess in some small companies they may not have the competence to select their first programmer. This blog mentioned Codility, a way to test a candidate's programming skills.

I headed over and liked the design and thought I'd take the demo test. I recommend you give it a go and come back after that.

It was a neat and easy to understand interface. I selected C as it's my weapon of choice for everything except for applications that need extensive string handling (in which case the String class makes bothering with Java worthwhile).

They had a fair problem and a suboptimal solution as a framework. After coding my most intuitive solution (for those who tried the demo, getting the righthand side total then:

for(i=0;i<n;i++){
  rsum -= arr[i];
  if (lsum == rsum) return i;
  lsum += arr[i]; }

To avoid arithmetic overflow, the array consists of doubles to be on the safe side. I overlooked this the first time in.

Anyway, in the 30mins I got it except for the overflow, which I went back and checked that it worked. I wish there were a few more tests like this as work doesn't exercise all my c muscles :) Props to Codility hopefully a thing of the future.

Round up of the Google AI Competition

Well the competition got a lot harder once the maps changed, the real top bots certainly rose to the top. Congratulations to the winners!

My reflections on the competition:

• Nicely run and nice that it adapted to the demands of the players
• Great to have the ability to watch the matches afterwards.
• Some very talented AI guys out there - with a fair bit of time on their hands.

My bot:

• Instead of doing a minimax on my move then the opponents move, it should have used the syncronous nature of movement to analyse the 9 (apart from the first move with all 4 directions available to both players) feasiable options.
• I would have ideally trimmed the resultant decision tree in a logical manner, searching deep on both sideways options and that would often beat the opposition, by adventagously cutting the areas.
• My initial implimentation of 'first to the most squares' was buggy, it would have been great to sort it out. so the bot didn't make such obvious bad moves.
• Using a more optimized 'first to most squares' algorithm. I should have made a list of the coordinates to go over in the next run, meaning that only 1-20 squares were checked rather than all squares.

I lacked the time to impliment these options, but that's no excuse, just the way it was. I had great fun and I'll be looking for the next challenge from the University of Waterloo CS Club.

I'll throw my code up here for anyone that wants a slightly buggy (but very fixable) tron bot.

In fact I have a few versions - one in perticular was stable but didn't search very deep.