A dynamic bracketing macro in LaTeX

latex 2014-01-16
I was cleaning up my LaTeX header and re-coded some macros to suit my needs better. I have always had a macro called \of which takes one parameter. It used to be the very simple macro 
\newcommand{\of}[1]{\left(#1\right)}
However, I sometimes want to specify the size of the brackets explicitly, so I wanted to add an optional argument to this macro such that \of[big]{\sum} will expand to \bigl(\sum\bigr). Sometimes I even want it not to do any resizing of the brackets at all. The correct way to do this is is \csname and \endcsname which allows you to delay expansion of a macro. Inside a macro definition, the command 
\newcommand{\ar}[1]{\csname#1arrow\endcsname}
will be such that \ar{right} is first made into \rightarrow and then expanded. We will use that to make \bigl and \bigr out of the argument big, for instance. Do you want to know more?

Python to Batch!

code 2014-01-13
Nikolai asked me how to open a Python interpreter prompt from the console with a certain module already imported. For the record, the Python command line switches tell us that python -i -m module is the way to start the prompt and load module.py. That made me wonder whether I can stuff it all into one batch file, and I came up with the following test.bat: 
REM = '''
@COPY %0.bat %0.py
@python %0.py
@DEL %0.py 
@goto :eof ::'''
del REM
for k in range(70):
    print(k)
That script will ignore the first line because it is a comment, then copy itself to test.py, then launch python with this argument. Afterwards, test.py is deleted and the script terminates without looking at any of the following lines. Note that :: is yet another way to comment in Batch. Python, however, will see a script where the variable REM is defined as a multi-line string and deleted right after that. After this little stub, you can put any python code you want. Well. I thought it was funky.

My new LaTeX editor, shiny UTF8

latex 2014-01-07
I have found and quickly begun to love a wonderful piece of software called TeXStudio. It's an open source LaTeX editor with preview pane and the preview is for the actual PDF document, not yet another buggy DVI viewer that fails to display your TiKzPictures correctly. It's available on all platforms. You have to seriously work through the (advanced) options and set it up to your liking ((This will most likely include shutting off all of the autocomplete features because they might otherwise drive you insane.)) , but I must say that this is probably the best LaTeX editor I have ever seen. Most prominently, it allowed me to switch all my projects to UTF-8 for the first time, because you can set file encoding in a comfortable way. It also does a good job at detecting UTF-8 and if everything fails, you can use the special comment !TeX encoding = UTF-8. Citing french papers has become slightly less of a torment.

Android Update auf einem in Deutschland gekauften Motorola Milestone 2

technology 2013-12-26
Meine Mission: Die App Withings Health Mate für das Withing Pulse auf meinem Motorola Milestone 2 zum laufen bringen. Zeitansatz: Der erste Weihnachtsfeiertag Status: 23:56 und erfolgreich. Möchtest du mehr wissen?

A very ample Definition

mathematics 2013-12-24
I was talking to this fellow mathematician, and told him how for my very personal taste, the research in algebraic geometry has sailed a bit too far ashore from the original question that motivated the subject: A classification for the solutions of polynomial equations. I told him that most of the heavy machinery in algebraic geometry can be given very good intuition - however, most courses neglect to do so. Anyways, he was clearly amused and not quite in belief of my radical position that unconditional and solitary abstraction isn't the only way to do algebraic geometry. He teased me to then tell him what an *»ample«* line bundle was, without talking about tensor powers or commutative diagrams. So, that's the reason for this post. I answered that ample line bundles are precisely those that induce finite morphisms to projective space, but I couldn't remember where I knew it from. I searched through all the major literature and could not find a reference until someone on Mathoverflow helped me out. Since I complained so much about how noone ever gives intuition to these kinds of concepts in algebraic geometry, I decided I'd blog a bit about line bundles and how you should think about them. Do you want to know more?

eMail obfuscation from several directions

code, technology 2013-11-08
It would be beneficial to have your eMail-Address on your homepage when you want to give people the opportunity to contact you. In my case, I actually want to give people that opportunity ((That does not go without saying: In some cases it is very important to discourage people from contacting you directly. For instance, it could be that you are usually not the right person to ask, but you get flooded with requests that you have to manually redirect elsewhere: It would be better if people got discouraged from contacting you while finding it very easy to contact the person that can actually help them.)). However, we all know that there are villains out there who harvest emails from websites in order to sell them to spammers. Hence, you would want to obfuscate your eMail-Address in such a way that it cannot be read from the HTML source code of the website easily. It goes without saying that naive obfuscation techniques like mymail(at)domain(dot)com are beaten more easily by machines than by people, and the more creative you get with your substitutions, the easier the machines can do it and the less easy your customers can. Images are the end of that line of thought, the point where a user has no chance at all other than to copy your eMail address letter by letter from an image which could still theoretically be OCR'd by a decent program. Therefore, Javascript methods to encode and on-the-fly decode the eMail address ((Famous enodings are ROT13, Base64, etcetera.)) seemed like the best choice to me for a long while. It is harder to run a Javascript interpreter than simple regular expressions for the email harvester, but to a user there is no difference: The browser already comes equipped with Javascript. At this point, some people get cranky that everything should work also without Javascript, and I can understand that. However, the main reason for me to abandon the Javascript method was simple necessity: I have to publish my eMail on the homepage of a university, which is managed from within a complex CMS, and the system would not allow me to use Javascript. This makes a lot of sense, you don't want every user of a large webportal to be able to stick whatever Javascript they like into the page, that stuff can make everything go to hell. This blog post is one among many advertising the capability of unicode to display letters from right to left. However, seriously, how difficult do you think it is for an email harvester to check for reversed email addresses as well? I would suppose it's more or less just a matter of checking for the reversed regular expression, too. Easy prey, if you ask me. But I had an idea! Do you want to know what that idea was?

Show Text File on Windows Desktop as Background

productivity, technology 2013-11-02
Finally there is an official way of setting a text file as your Desktop Background: Windows Sysinternals BgInfo. This tool can show a lot of information about your system but may also show the contents of a Textfile: Press the button Custom... on the right and then New.... There you may select Contents of a file and include a path to the text file. After you saved the BfInfo config file somewhere on your system, you can call BgInfo in the following way to update the background image: 
bginfo c:\System\config\bginfo.bgi /timer:0
This may be useful to show log files that you want to keep an eye on or the shadowfile of your favorite TaskWarrior report.

Shell completion in TaskWarrior

productivity 2013-10-28
There are scripts to enable shell completion in TaskWarrior (e.g. for projects and tags). Since I use cygwin with mintty this one was suitable for me. I added the lines 
complete -o nospace -F _task t
complete -o nospace -F _task task
complete -o nospace -F _task ta
at the bottom though to support the shortcuts t and ta.

The Eisenhower Matrix in TaskWarrior

productivity 2013-10-24
The Eisenhower Method is based on the simple understanding that urgency and importance are not the same (see for example The Eisenhower Method with a picture of the "matrix" at Wikipedia). The goal of this post is to implement it with TaskWarrior. Do you want to know more?

Launching Applications under Windows

productivity 2013-10-22
How do you launch applications under Windows? More precisely: How can you optimize this? I haven given this question some thought and tried a program called Quick Key Launch. If you are interested, you can find more details in my article.

Reset Password on Windows 7 System

technology 2013-09-17
Boot with a System Repair disc, select the correct installation, start a command prompt and replace the utilman.exe executable with cmd.exe in system32 (maybe you should create a backup first): 
copy d:\windows\system32\cmd.exe d:\windows\system32\utilman.exe
The drive letter shifts up by one because C: is occupied by a system reserved partition that is normally hidden. Then boot the computer with your Windows 7 installation and click on the small pie-like icon in the lower left corner of the screen. This now starts a command prompt instead of utilman.exe. With net user, you can list all users and with net user MYUSERNAME MYNEWPASSWORT you can set the password of any user.

Install TaskWarrior under Windows for dummies

technology 2013-09-13
The short version of this post is: Install cygwin together with the package "task". Here is a slightly longer version, if you want to know more!

Reverse md5 hash

technology 2013-09-04
We all know, that md5 has its weaknesses. But, as always, exploiting such weaknesses in practice is not a piece of cake. Do you want to know more?
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