Guy – Page 26 – Guy Rutenberg

Displaying Non-Builtin Math Macros in LyX

I believe LyX is a great tool for writing LaTeX document. It makes writing formulas very easy and it allows you to see the formula as you are writing, as opposed to seeing only LaTeX code. However LyX doesn’t support every LaTeX package and the macros it defines. Sure it doesn’t stop you from using these macros in your formulas, but it doesn’t display nicely, you see the name of the macro instead of a schematic preview.

While LyX doesn’t support many of the great packages out there like mathtools (which I really hope it will someday), you can add some support to your documents. At the beginning of the document insert a comment, via Insert->Note->Comment. Inside the newly created comment insert a math-macro via Insert->Math->Macro. In the name part, put the name of the command you want to add support for. In the second box (caption LyX), use existing LyX commands to mimic how the macro will look like. For example, this is what it looks like for the \coloneqq macro (from the great mathtools package):
$math-macro$

After adding the math macro in the comment, when you will use the macro inside formulas it will display nicely:
$math-macro2$

A little explanation how things work. When you define a math macro in LyX, LyX does two things:

Inserts LaTeX code to create the macro.
Displays the macro nicely when editing the document.

While the latter is desirable, the former is problematic. If LyX inserts LaTeX code to define the existing macro, it will cause errors. So when you put the LyX macro in the comment environment, the code LyX generates gets ignored and only the second, desirable, outcome is achieved.

Convert `int` to `string` (As Well As Almost Anything)

This is a little code snippet from Open Yahtzee‘s code base that converts all the built-in types and many custom classes (ones that override the << operator) to string.

template <class T> inline std::string stringify(T x)
{
	std::ostringstream o;
	o << x;
	return o.str();
}

I first wrote it to convert ints to string, but later I templatized it so it would work with other types as well. It’s a clean elegant snippet that I thought other might find useful too.

`tarsum`-0.2 – A read only version of tarsum

When I first scratched the itch of calculating checksums for every file in a tar archive, this was my original intention. When I decided I want the script in bash for simplicity, I forfeited the idea and settled for extracting the files and then going over all the files to calculate their checksum value.

So when Jon Flowers asked in the comments of the original tarsum post about the possibility of getting the checksums of files in the tar file without extracting all the archive, I’ve decided to re-tackle the problem.

Continue reading tarsum-0.2 – A read only version of tarsum

XWRDS Gets a Browser Search Extension

I’ve added today an OpenSearch description for XWRDS. In simple words it means that you can now search XWRDS directly from your browser search box. Supported browsers include Firefox 2.0+, Internet Explorer 7+ and Google Chrome, so if you use one of this browser you can now solve your crosswords faster then ever by using the XWRDS search.

To add the XWRDS search to your browser’s search box either click this link, or got to the XWRDS website and select the XWRDS search engine from the pull down menu of your browsers search box (usually at the top right corner of the window).

XWRDS Gets a YubNub Command

YubNub is a site that provides users with a social command line to the internet. It lets you do all kinds of stuff, mostly search related, by typing special commands.

Today, I’ve added a command to YubNub that allows you to search XWRDS. The command name is xwrds and it expects the clue to search as an argument.

For example:

xwrds Either of two of the VIII's six

I hope people will find it a convinient way to easily search XWRDS.

Update 20/11/2009: Fixed link to YubNub.

RTL Tiddlers in TiddlyWiki

Update – For TiddlyWiki 5 see RTL Tiddlers in TiddlyWiki 5.

I’ve been using TiddlyWiki for a while now, and it became a very useful tool for me. Today, I’ve decided to organize my various recipes (somehow cooking and especially making deserts has turned into an hobby of mine), and as you can expect I’ve decided to use TiddlyWiki for the tasks.

There was a slight problem as some of the recipes are in Hebrew, and it seems TiddlyWiki doesn’t have built-in support for RTL (right-to-left) tiddlers. However, such support can be added via custom stylesheets and the tiddlers’ tags. The idea for this method is taken from this TiddlyWiki.

Create a new tiddler called “StyleSheet” (without the quotes). This is a special tiddler (a shadow tiddler) that lets you add additional CSS code for your wiki. Insert the following code into the newly created tiddler:

/*{{{*/
div[tags~="RTL"].tiddler {
    direction: rtl;
}
div[tags~="RTL"].tiddler .subtitle {
    direction: ltr;
}
div[tags~="RTL"].tiddler .tagged {
    direction: ltr;
    float: left;
}
/*}}}*/

Now for every tiddler you want to be in RTL direction just add RTL to its list of tags. After you do it, the tiddler will appear correctly. Here is an example of what in RTL looks like after the fix:

Italian Radio Stations List for Radio.py

Fabio, an Italian user of radio.py, wrote to me the other day with couple of suggestions and a huge radio.py configuration file with 150 Italian radio stations.

According to Fabio, the list contains 40 of the most popular Italian radio stations, along with radio station from where he used to live in north Italy.

In his post, Fabio also describes a useful tip he uses. He used the radio.py configuration file to number his favorite stations, thus allowing him even easier way to listen to them. E.g.

radio.py 1
radio.py 3

Previously, Henrikan compiled a .radiopy file containing some 58 Swedish radio stations.

If your a radio.py reader and you’ve compiles a .radiopy file you would like to share, send a link along with short description and I’ll gladly publish it.

Iptables Cheatsheet

From time to time I find myself having to go through man pages and googling for some simple iptable rules. This post is meant as a cheatsheet for me, so I can concentrate here various rules and remarks.

I hope others will benefit from this cheatsheet as well. Intend to expand it over time as I gather more rules and tips, so bookmarking the post might be a good idea. Last but not least, if you have some useful iptables rules I’ve missed please send them using the comments.
Continue reading Iptables Cheatsheet

Starting `tracd` without Root Privileges at Startup

I use Trac for the Open Yahtzee website. I’ve decided to use tracd for serving the requests (due to a configuration issue I didn’t want to mess with), which required starting it each time the server restarts. I’ve already written one solution for it, in the form of an init.d script for tracd. However, it bothered me that the tracd runs with root privileges which it doesn’t really requires.

After searching a bit I’ve found out that cron can run tasks on startup using the special @reboot keyword instead of the normal time fields. So edit your crontab and add the following line:

@reboot /usr/bin/tracd --daemonize --pidfile=~/run/tracd.pid --port=PORT --hostname=HOSTNAME -s TRAC_ENV

Just replace PORT, HOSTNAME and TRAC_ENV with the appropriate values for your environment, and make sure you got a run/ sub-directory in your home folder (or change the pidfile value).

To stop the server just do:

kill `cat ~/run/tracd.pid`

While there is no straight way to restart the server (like /etc/init.d/tracd restart), it’s a good compromise for dropping root privileges.

Amarok Sleep – Stop Playback After Specified Amount of Time

Amarok is my favourite music player. I like to listen to music when I go a sleep, but I don’t want the music to keep playing all night long. This is why I’ve added a sleep feature to radio.py. Unfortunately, Amarok doesn’t have a built-in sleep functionality, but the Amarok developers left open door for us to implement it with ease by means of interfaces allowing to control amarok from the command line.
Continue reading Amarok Sleep – Stop Playback After Specified Amount of Time