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As I am currently working on my master’s thesis in astronomy, I regularly have to handle large amounts of data. Fortunately tools, such as NumPy, SciPy and numexpr, have been developed to make it easy to do computations on large dataset very fast.

A few days ago, however, I found myself needing to do a plain old for-loop…
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I have just started to use Arch Linux as my primary OS, and this has of course required a great deal of configuration. My first problem was to make Caps Lock behave as an additional Ctrl, but it turned out to be quite simple:

Try to write the following three lines in a terminal:

xmodmap -e "clear Lock"
xmodmap -e "keysym Caps_Lock = Control_L"
xmodmap -e "add Control = Control_L"

If this works, go to your home directory and make a file called .Xmodmap (the capital X is very important!). Then write the following in that file:

!! Map Caps to left Control
clear Lock
keysym Caps_Lock = Control_L
add Control = Control_L

Now the configuration should load each time the computer starts. If it still doesn’t, then try to look in the file /etc/X11/xinit/xinitrc for a line that begins with usermodmap=. Whatever stands on the right hand side of the equals sign is the file you need to put the configuration in.

Installation of Maple 10 works great on Windows, however there is a minor problem on Linux which must be fixed for the installation to work.

1. First we need to copy the contents off the cd. Open a terminal and make a new directory, e.g.

   mkdir /tmp/maple10

   Next, change to the cd-rom directory and copy the entire content to the new directory:

   cd /media/cdrom
   cp -a * /tmp/maple10/

2. Now we need to change the script of the installer a bit. First get to the right directory:
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What is SVN? And why should I use it?

Subversion, or SVN, is a version control system (VCS). If you aren’t sure what a VCS is, you should read this nice introduction: http://progit.org/book/ch1-1.html

The introduction is from a book on the Git version control system. I don’t claim to be anything near an expert on VCS’s, so I can’t say if SVN is better than Git or vice versa. It just happened so that I learned SVN, and since I’m quite fond of it, I have made this small guide on how to get started using SVN.

This guide has been written for the physics students at Copenhagen University, but even if you aren’t one of those lucky guys, you should still be able to copy most of it.

I should also note that this guide has been written with Linux in mind. SVN can of course be used on Windows or Mac as well, but I have not worked with it myself, so it will not be covered here.

Using SVN

The overview

Using SVN can basically be described like this:

• You create your project on a server. The server keeps track of all changes to the project.
• You make a ‘link’ (a directory) on your computer to the project on the server.
• You can then easily upload and download changes to the files because your computer is ‘linked’ to the server.

I’ll walk through these steps below.

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