## Sunday, June 29, 2008

### LaTeX clever references

When you're referencing a section in LaTeX, you'd usually write something like
… as we saw in section \ref{sec:cake}.
But this is somewhat inconvenient. LaTeX knows that it's a section, right? So why the need to specify this? Worse, if you ever change it into a subsection, your reference will be wrong.

Luckily there's the command \autoref from the hyperref package. However, this too has some drawbacks, mainly that it does not provide a capitalised version. A better alternative is to use the package cleveref. It is not in the Ubuntu repositories, but you can simply download and extract the archive, then run latex cleveref.ins to obtain cleveref.sty and dump it in the directory along with your document.

\usepackage{cleveref}
and make sure it's the last package to load; that is, even laster that hyperref.

Using \cref the previous example becomes:
… as we saw in \cref{sec:cake}.
This will produce the text “… as we saw in section 3.”. At the start of a sentence you'd use the capitalised version \Cref:
\Cref{sec:cake} gives the recipe …
You can even write:
See also \cref{sec:cake,sec:lie,eq:recipe,thm:delicious}.
This produces “See also sections 2 and 3, eq. 5 and theorem 1.” Although I doubt that anyone would use this very often, it's still pretty cool.

You can customize the word that is printed before the number. For example, some people like them to be always capitalised. (I don't, but my supervisor does, and who am I to argue?)
\crefname{chapter}{Chapter}{Chapters} \crefname{section}{Section}{Sections} \crefname{subsection}{Section}{Sections} \crefname{subsubsection}{Section}{Sections} \crefname{figure}{Figure}{Figures} \crefname{table}{Table}{Tables}
Etcetera. Note that subsections and subsubsections are usually all referenced to as sections.

Finally, as a bonus, here's how you make it work with references to \subfloats from the subfig package:
\crefname{subfigure}{Figure}{Figures}
(Capitalise according to taste, or even write “subfigure” if you like.)

For more options, see the cleveref documentation.

## Thursday, June 12, 2008

### mplayer tricks

mplayer is my favourite movie player for Linux by far, but the thousands-of-lines long manual page can be a little daunting. Here I've compiled a list of some options that you may or may not know, that I find useful in day-to-day movie playing.

-cache 8192
Sets the cache (buffer) size to 8192 kilobytes. Useful when playing over a network connection that occasionally hiccups, like mine.
-fs
Start fullscreen playback right away. Especially useful when playing multiple movies in a single command, to prevent dropping back to windowed mode at each new movie.
-monitoraspect 16:10
If your monitor has non-sqare pixels (e.g. 1280 by 1024 on a 4:3 monitor), you can specify the physical aspect ratio of your monitor in this way.
-ao alsa
Use ALSA for sound playback. Should be the default in any decent distro, but in case it doesn't work, try this (or, heaven forbid, -ao oss).
-nolirc
Disable LIRC support. Gets rid of the annoying “Failed to open LIRC support.” message.
-subfont-text-scale 3
The default subtitle size is 5, but I prefer mine to be a little smaller.
-aspect 4:3
Overrides the aspect ratio of the movie. Some useful values are 4:3, 16:9 and 2.35.
-vf cropdetect
For movies with black bars around them. This detects the black bars in the image and prints out the correct argument to crop them off, such as-vf crop=656:288:0:0. One of mplayer's coolest features.

Options can also be put into a file ~/.mplayer/config if you leave out the initial - and replace spaces by = characters (e.g. monitoraspect=16:9). Saves a lot of typing!

## Wednesday, June 11, 2008

### Integrating Inkscape graphics in LaTeX

Getting good-looking diagrams and figures into a LaTeX document can be tricky. My favourite software (and I think it ought to be anyone's favourite) for drawing such figures is Inkscape. This post explains how to get text in the proper font into Inkscape, how to put equations into Inkscape drawings, and how to get those drawings out of Inkscape and into your LaTeX document.

It is a good idea to use the latest version of Inkscape, because the program is rapidly being improved all the time.

#### LaTeX font in Inkscape

To make your figure look good in its environment, you can use the same font family that the surrounding body text uses. In LaTeX's case: Computer Modern.

##### Installing fonts

As Computer Modern is written in the METAFONT format, it cannot be directly used in Inkscape. For that, we need the font in OpenType (OTF) format, preferred for Linux (and MacOS?) systems, or in TrueType (TTF) on Windows. (Side note: here's an interesting article on the differences between all the font formats.)

The BaKoMa font bundle provides the Computer Modern font in these and some more formats. Download it here, then extract to a temporary directory. Installation is as follows:

Windows
Open up Fonts in the Control Panel and drag-and-drop all files from the ttf directory into here.
Ubuntu Linux
Open a file browser (Nautilus) and navigate to fonts://, then drop the fonts from the otf directory here. You may need to run Nautilus as root using the command gksudo nautilus.
Non-Ubuntu Linux (and Ubuntu Hardy, because they broke it)
Copy the files (as root) from the otf directory to anywhere you like inside /usr/share/fonts, then run sudo fc-cache -fv. (For a single-user installation, ~/.fonts might work, but no guarantees!)
##### Creating the figure

If you start Inkscape, new fonts with names like BKM-cmr10 should be available. Here, cm stands for Computer Modern, r means roman (normal body-text font) and 10 is the point size. Simply use this font for all the text in your illustrations to make them integrate seamlessly with the text in LaTeX.

Or, almost seamlessly. It seems that Inkscape (version 0.46) does something strange with the font size, or the BaKoMa fonts are too small to begin with. In any case, I find that using BKM-cmr10 at 12 points in Inkscape provides the best match to the default 10-point LaTeX body font. I personally prefer BKM-cmss10, the sans-serif version of Computer Modern, because it integrates nicely with abstract line drawings and with the surrounding serif body text, but if you use mathematics in you figures this is probably not an option.

#### LaTeX equations into Inkscape

Yes, it is possible to add mathematical symbols and equations to your Inkscape drawing! You can also use this for normal text, but it is more cumbersome than the font approach detailed above.

##### Installing textext

First, you need textext. Simply extract the two files from the archive into /usr/share/inkscape/extensions for a systemwide installation, and fix the permissions:
sudo chmod 644 textext.inx sudo chmod 755 textext.py
(For a single-user installation, ~/.inkscape/extensions should work.)

You'll need some extra packages for the script to work. On Ubuntu:
sudo apt-get install python-lxml sudo apt-get install pstoedit
On non-Debian based Linux distributions, install pstoedit and the Python lxml package in some other way. On Windows, see the textext web page for details.

##### Using textext

Now (re)start Inkscape, click Effects, Tex Text and type your LaTeX code! You can even load a preamble from a file to include additional packages such as amsmath. (Unfortunately the file must contain only the preamble, not an entire document.) The same problem occurs as with the previous approach: you need to set a scale factor of 1.25 to (approximately) match the font size of the LaTeX document. Close the dialog with the OK button or with Ctrl+Enter.

The equation (or other LaTeX text) is then placed as a group of shapes into Inkscape. To edit it (yes, that is possible!), select it and click Effects, Tex Text again. This feature is a little feeble, however: do not ungroup the text object, or else it will become uneditable.

#### From Inkscape to LaTeX

##### Exporting from Inkscape

When the figure is done, deselect all objects, then go to Document Properties and click Fit page to selection. This will adjust the page boundaries to fit exactly around all objects. Then save the figure to Inkscape SVG format (for later editing), but also save a copy as “PDF via Cairo”. Check the box to Convert text to paths, because otherwise the kerning seems to be messed up in the export.

##### Including in LaTeX

This is a simple matter of
\usepackage{graphicx}
in the preamble, and then placing the figure using
\includegraphics{diagram.pdf}
as usual. Do not use any of the scaling options of \includegraphics, since they will cause the text in the figure to scale as well, and it will no longer match the size of the surrounding body text.

Compile your LaTeX document using pdflatex (not normal latex, since that only handles inclusion of EPS files), and there you go!