My notes bin

dia2code generates code from UML diagrams in Dia. Binaries are not available for Mac OS, so we must compile it from source. The README file is very useful for a quick guide to installing and using dia2code. Compiling dia2code is quite simple and often successful. However, when we run it, we may get the error saying that dia2code requires libxml2 version 12.0.0 or later, while the pre-installed libxml2 on Mac OS is at version 10.0.0. To update libxml2 on Mac OS, use homebrew to install libxml2 and libxsltbrew install libxml2 libxslt

However, libxml2 and libxslt by homebrew are keg-only, meaning that they are not linked to /usr/local as this might cause conflicts with the pre-installed libraries. To compile dia2code (or any code for that matter) with the homebrew's installed libraries, we need to specify the libraries explicitly. For dia2code, run configure as follows:

LDFLAGS="-L/usr/local/opt/libxslt/lib -L/usr/local/opt/libxml2/lib" CPPFLAGS="-I/usr/local/opt/libxslt/include -I/usr/local/opt/libxml2/include" ./configure

Computer vision for dummies

When writing my thesis, I created a table. However, some columns have unequal widths, which looks awful. So I used the paragraph column type (p) to specify their widths. The problem is that they are left-aligned while I want them centered.  I then used the array package and use the prefix specs >{\centering}, but it caused error due to the new line command (\\) being changed. To fix this, you need to specify >{\centering\arraybackslash}. The final code is:

This manual page instructs how to share LaTeX definitions (e.g. in your paper) with pictures created in IPE. However, that solution did not work for me. I figured out a simpler solution:

In IPE, use menu "Help/Show Configuration" to see which directory is used for temporary LaTeX files; in my case, it is ~/.ipe/latexrun.

Copy the LaTeX definition files that you want to use to that directory.

In IPE, use menu "Edit/Document Properties" to edit the preamble to input these files.

I've just discovered today that the way LaTeX handles delimiters, like (, ), [, ], is very very complicated.

Basically, those delimiters can be treated in two ways (or two types):

Ordinary atoms: as the name suggests, they are just ordinary atoms and there is no special handling taken.

Open and close atoms: they open and close some inner atoms, for example in cos(x), the delimiters ( and ) open and close the inner atom x OF the operator cos.

The visual difference may not be too obvious. In the first case (ordinary atoms), there is often some thin space before/after the delimiters. In the second case, there is none (space = 0). So, using the same example cos(x):

Ordinary atoms: there is some thin space between 'cos' and '(' and between ')' and what follows. This is undesirable because it detaches the operator cos and its parameter.

Open and close atoms: there is no space between 'cos' and '(' and between ')' and what follows. This is desirable because the contents inside the parentheses is the parameter of the operator cos.

Surprisingly, \left and \right produce ordinary atoms instead of open/close atoms.

\left, \right, \big, \bigg, ... produce ordinary atoms.

(, ), [, ], \lvert, \rvert, \lVert, \rVert, \bigl, \bigr, \biggl, \biggr, ... produce open/close atoms.

So, to summarize:

Avoid using \left, \right after operators.

After an operator (such as cos, sin, log, sum,...) whose parameters are the inner contents of the delimiters, use the plain delimiters or their \<size>l, \<size>r friends, so that open/close atoms are produced correctly.

Note that the matrix environments (bmatrix, pmatrix,...) use \left, \right (producing ordinary atoms).

The package mleftright might be of interest. It defines \mleft and \mright to produce open/close delimiters for \left and \right. It provides a command to re-define all \left and \right to \mleft and \mright.

References:

http://tex.stackexchange.com/questions/2607/spacing-around-left-and-right

http://tex.stackexchange.com/questions/19480/why-the-control-sequences-bigl-biggl-bigr-or-biggr-as-i-can-always-use-b