Carl’s notes

We just purchased an Asus EeePC thinking it would be a nice compact laptop to run experiments on. It has bluetooth, wifi, 3 USB ports, several hours of battery life, a solid state harddrive and runs Xandros Linux.

First impressions were very good, it really is small and light for a laptop. I was able to connect to a WPA2 wifi access point immediately and do some Skype video conferencing.

The trouble started when we tried to set up the machine to run our own software. It seems that anything not quite standard such as changing the keyboard mapping isn’t possible with the provided configuration tools.

• To open a terminal press Ctrl-Alt-t.
• If you want to restore the complete system to its default state press F9 at startup to access the restoration menu. Presumably this only works if you haven’t modified the partitions.
  To install packages such as subversion, g++ or pygame you need to add some repositories as indicated on this other blog.
• Running sudo apt-get update and then sudo apt-get upgrade fails with no space left on device. df -h shows that / only has a few hundred megabytes free. Apparently the 20 gigabytes available are split over two solid state drives, a fast 4 Gbyte one and a slower 16 Gbyte one. The 4 Gbyte drive has 2 Gbyte taken up by the hidden restoration partition. This is quite confusing but essentially means that there is hardly any space to install extra software or even to update the system. You can recover a little space by running sudo apt-get clean or sudo apt-get autoclean to empty the contents of /var/cache/apt/archives/ but you will probably need to then run sudo dpkg --configure -a and maybe reinstall some broken (truncated) packages.
• Java 6 doesn’t seem available in any of the EeePC repositories and takes too much space anyway so I manually extracted Sun’s archive into /home/software/.
• The Xandros Linux distribution on the EeePC doesn’t seem to use the usual bluez bluetooth stack. Instead it uses something called AzureBT. This works fine for sending files via the EeePC interface but doesn’t work with the Python bluetooth module for instance. You will get the error address family not supported by protocol. Same error if you install bluez-utils and run sudo hciconfig or hcitool dev. Several posts on the eeeuser forum discuss this problem, in particular this one and this one. I renamed /lib/modules/2.6.21.4-eeepc/kernel/net/bluetooth/bluetooth.ko.2.6.21.4 and /lib/modules/2.6.21.4-eeepc/kernel/drivers/bluetooth/hci_usb.ko.2.6.21.4 to bluetooth.ko and hci_usb.ko respectively. Then I added hci_usb and rfcomm to the bottom of /etc/modules, and dbus and bluetooth to the bottom of /etc/fastservices. After a reboot hcitool dev and sudo hciconfig both give me plausible output but the bluetooth icon in the taskbar shows that bluetooth is disabled and says For some reason, please restart AzureBT again.
• The EeePC will display correctly on an 800×600 head mounted display connected to the VGA port but by default not on both the LCD and the external display at the same time. Thinkwiki shows how to resolve this using xrandr. You need to edit xorg.conf and change the Virtual lines to 2048 2048. This tells xorg to reserve enough graphics memory to allow a Virtual screen 2048×2048 pixels. This will allow you to have two 1024×768 screens next to each other or one on top of the other. Restart X with Ctrl-Alt-Backspace and then run xrandr --output LVDS --auto --output VGA --mode 800x600 --below LVDS to extend the desktop to both displays. The taskbar and the desktop might move to the external display and the desktop might resize so it doesn’t fill the whole screen but this maximised windows will still fill the whole screen correctly.

I mentioned the eeeuser forum but the Asus support forum might also provide some help.

Here is a Matlab implementation of the Douglas-Peucker polyline simplification algorithm. It takes a polyline and removes as many vertices as possible without changing the shape too much. This code is ported from the C++ version at SoftSurfer. I’ve included some sample data to test the function.

EDIT: I just found a Python implementation which is iterative rather than recursive, unlike the Matlab one. It’s based on a freely-licensed C++ implementation.