At present I don’t have much time for the blog because of my work, but I keep on reading and answering questions and comments.

For instance since I’ve noticed a link by Uwe to a table related topic and because of Oliviers comment there I’ve added another comment to “Fancy tables with TikZ“. It shows a tikz-matrix based table, seperating the actual implementation from the table contents. A simple code like

\begin{mytable}{1.2cm}{2.4cm}{1.2cm}{0.6cm}{
   \head{Rank} & \head{Distribution} & \head{Hits} & \\
   1 & Ubuntu & 2114 & \down \\
   2 & Fedora & 1451 & \up   \\
             ...
  10 & Arch   &  625 & \down \\
}
\end{mytable}

produces the following output.

Changing the style of tables in the whole document is easier when they are defined as new environments in the preamble. For instance the mytable environment could be implemented without TikZ using just the standard tabular environment without changing the usage of those tables. Likewise with \head - I avoid using \textbf directly. It allows to change the look of the headings in a consistent way by formatting logically.

Comments and suggestions are always welcome, perhaps following the original post “Fancy tables with TikZ“.

Today I wanted to create a table for a presentation and I remembered a suggestion made by Kjell Magne Fauske in comp.text.tex in August 2008, to use TikZ to create tables with rounded corners. I’ve investigated this idea further to achieve a colorful table layout in a shape that’s unusual for LaTeX. Here’s the result, displaying a ranking of Linux distributions produced by DistroWatch.com:

Click on the image to see it bigger, for a complete view open the pdf presentation.

The table has been put into a TikZ node, both at the top and at the bottom of the table I’ve used rectangles with rounded corners and some shading. A third rectangle is used to overlay parts of the other two rectangles.

The complete source code:

\documentclass{beamer}
\usetheme{default}
\usepackage{amsmath}
\usepackage{tabularx}
\usepackage{booktabs}
\usepackage{colortbl}
\usepackage{tikz}
\usetikzlibrary{calc}
\pgfdeclarelayer{background}
\pgfdeclarelayer{foreground}
\pgfsetlayers{background,main,foreground}
\setbeamertemplate{background canvas}[vertical shading]%
  [top=blue!1,bottom=blue!30]
\setbeamertemplate{navigation symbols}{}
\newcommand*\up{\textcolor{green}{%
  \ensuremath{\blacktriangle}}}
\newcommand*\down{\textcolor{red}{%
  \ensuremath{\blacktriangledown}}}
\newcommand*\const{\textcolor{darkgray}%
  {\textbf{--}}}
\begin{document}
\begin{frame}[bg=lightgray]
\textbf{\Large Linux distribution ranking,
        26th August 2009}
\begin{center}
\begin{tikzpicture}
\node (tbl) {
\begin{tabularx}{.6\textwidth}{cXrcc}
\arrayrulecolor{purple}
\textbf{Rank} & \textbf{Distribution} &
  \textbf{Hits} & \\
1 & Ubuntu\rule{0pt}{2.5ex}  &  2114 & \down \\
\midrule
2 & Fedora & 1451 & \up \\
\midrule
3 & Mint & 1297 & \const \\
\midrule
4 & OpenSUSE & 1228 & \up \\
\midrule
5 & Debian & 910 & \down \\
\midrule
6 & Mandriva & 907 & \up \\
\midrule
7 & PCLinuxOS & 764 & \up \\
\midrule
8 & Puppy & 738 & \up \\
\midrule
9 & Sabayon & 671 & \up \\
\midrule
10 & Arch & 625 & \down \\[0.5ex]
\end{tabularx}};
\begin{pgfonlayer}{background}
\draw[rounded corners,top color=red,bottom color=black,
    draw=white] ($(tbl.north west)+(0.14,0)$)
    rectangle ($(tbl.north east)-(0.13,0.9)$);
\draw[rounded corners,top color=white,bottom color=black,
    middle color=red,draw=blue!20] ($(tbl.south west)
    +(0.12,0.5)$) rectangle ($(tbl.south east)-(0.12,0)$);
\draw[top color=blue!1,bottom color=blue!20,draw=white]
    ($(tbl.north east)-(0.13,0.6)$)
    rectangle ($(tbl.south west)+(0.13,0.2)$);
\end{pgfonlayer}
\end{tikzpicture}
\end{center}
\small
Data by DistroWatch.com, spanning over the last 6 months,
hits per day.
\end{frame}
\end{document}

It’s just a draft, some lengths have been adjusted to fit in order to demonstrate using TikZ with tables in a quick way.

If you’re using pstricks-add or a package requiring it consider updating it if its version is lower than 3.34. The version 3.34 has been released some days ago and brings a bugfix for the \pstScalePoints macro. The bug could look like the one discussed today in “problem with pstricks and \psset” on LaTeX-Community.org where v3.32 has been used.

Further the macro \psMatrixPlot has been modified in v3.34 and is now able to plot a matrix of n² values as an intensity plot.

Asymptote is a powerful descriptive vector graphics language useful for for technical drawing, using LaTeX for high-quality output. It’s not just a graphics program but a programming language. Asymptote is inspired by MetaPost but provides C++-like syntax. It runs on Linux, UNIX, MacOS and Windows. In a very mathematically oriented way you can create 2D and 3D graphics, here’s just a small example coming with the program:

Now it’s been released on CTAN, 19 May 2009.

For more information visit:

• the Asymptote package on CTAN,
• the Asymptote homepage.
  The homepage contains also
  • a gallery,
  • documentation,
  • Answers to frequently asked questions (FAQ),
  • a discussion forum and more.
• the forum Asymptote and GeoGebra on artofproblemsolving.com,
• the Asymptote Wiki also on AoPS,
• the Asymptote example gallery.

Asymptote can be used easily within LaTeX documents. There’s a good introduction by Dario Teixeira: Asymptote and LaTeX: An Integration Guide.

There are even more resources you can find if you follow those selected links.

In previous posts I’ve shown some examples how the TikZ graphics package could be used to draw mathematical diagrams like exact sequences and commutative diagrams. Felix Lenders has written a tutorial called Commutative Diagrams using TikZ dealing with this subject and has published it today. In that paper he’s describing basic syntax, styles, arrows, curves, positioning issues and more. The tutorial contains several examples with the corresponding source code.

To read related blog posts have a look at the TikZ category.

In the Art of Problem Solving Forum somebody asked for help in creating a construction for proofs and demonstrations in Logic by LaTeX commands. Math expressions should be aligned, some connected by arrows going vertically and horizontally.
Regarding arrows I would use tikz and also its matrix library for math nodes. The nodes could be connected by -| or |- path construction operations, like

\draw (node1) -| (node2) |- (node3);

For creation of the example given in the thread on AoPS I’ve used a matrix of math nodes, some empty nodes for alignment and |- -| arrows, here’s the compilable example code:

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{matrix}
\begin{document}
\begin{tikzpicture}[every node/.style={anchor=west}]
  \matrix (m) [matrix of math nodes,
    nodes in empty cells]{
    \quad & 1.\quad (x)(Q\supset Fx) & \\
    & 2.\quad Q\supset Fx & \textrm{I,\textbf{UI}} & \\
    & 3.\quad Q \\
    & 4.\quad Fx & 2, 3, \textrm{ M.P.}\\
    & 5.\quad (x)Fx & 4, \textrm{ \textbf{UG}} \\
    & 6.\quad Q\supset(x)Fx & 3-5, \textrm{ C.P.} \\
    & 7.\quad \parbox[t]{2.9cm}{%
             $(x)(Q\supset(x)Fx)\supset$\\
             $[Q\supset(x)Fx]$} & 1-6, \textrm{ C.P.}\\};
  \draw[-stealth] (m-7-2.north east)
               -| (m-1-1.west) |- (m-1-2);
  \draw[-stealth] (m-6-2.north east)
               -| (m-3-1.east) |- (m-3-2);
\end{tikzpicture}
\end{document}

Output:

When one edge of a graph passes over or under another edge there may be a small gap needed in the drawing of one of those edges. An easy trick is to draw the upper edge two times: first with the background color and more thickness, afterwards normally, like
<node1> edge [-,line width=6pt,draw=white] <node2> edge <node2>
Here’s an example diagram used in the definition of the pull-back of a Banach bundle:

The source code:

\begin{tikzpicture}
  \matrix (m) [matrix of math nodes, row sep=3em,
    column sep=3em]{
    & f^\ast E_V& & \vphantom{f^\ast}E_V \\
    f^\ast E & & \vphantom{f^\ast}E & \\
    & U & & V \\
    M & & N & \\};
  \path[-stealth]
    (m-1-2) edge (m-1-4) edge (m-2-1)
            edge [densely dotted] (m-3-2)
    (m-1-4) edge (m-3-4) edge (m-2-3)
    (m-2-1) edge [-,line width=6pt,draw=white] (m-2-3)
            edge (m-2-3) edge (m-4-1)
    (m-3-2) edge [densely dotted] (m-3-4)
            edge [densely dotted] (m-4-1)
    (m-4-1) edge (m-4-3)
    (m-3-4) edge (m-4-3)
    (m-2-3) edge [-,line width=6pt,draw=white] (m-4-3)
            edge (m-4-3);
\end{tikzpicture}

This topic was discussed on Matheplanet.com.

If you want to read more about commutative diagrams with TikZ have a look here: Chains with labeled edges.

These days I wanted to include some commutative diagrams in a math text. There are already packages designed for this purpose, like amscd and xy-pic. I’ve used xy-pic before and didn’t like its usability and output much. The most recent documents I found on CTAN were dated 1999, many links on its homepage were dead, though xy-pic still works fine today, also with pdflatex. But I decided to use pgf/TikZ now because it can be used to create graphics in many different ways. For instance the beamer class is using pgf already, so why not use it also for math diagrams.

For writing exact sequences the chains library seemed very useful, but I missed the feature to label the edges of a chain. Just arrows weren’t enough, I needed to write maps over, under or just next to it.

I decided to make a workaround by modifying the join method of the chain library. Its syntax is join=with<node> by <options>, I’m changing the syntax to join={node[options] {label}}, this is the code to achieve the effect wanted:

\tikzset{join/.code=\tikzset{after node path={%
\ifx\tikzchainprevious\pgfutil@empty\else(\tikzchainprevious)%
edge[every join]#1(\tikzchaincurrent)\fi}}}

Some general settings before starting the diagrams:

\tikzset{>=stealth',every on chain/.append style={join},
         every join/.style={->}}

Now a short exact sequence can be written for example:

\begin{tikzpicture}[start chain] {
    \node[on chain] {$0$};
    \node[on chain] {$A$} ;
    \node[on chain, join={node[above]
          {$\scriptstyle\varphi$}}] {$B$};
    \node[on chain, join={node[above]
          {$\scriptstyle\psi$}}] {$C$};
    \node[on chain] {$0$}; }
\end{tikzpicture}

Output:

For more complex diagrams you could use the matrix library to create matrices of math nodes, connecting the nodes by chains. Here’s the code for the Short 5-Lemma as example:

\begin{tikzpicture}
  \matrix (m) [matrix of math nodes, row sep=3em,
    column sep=3em]
    { 0 & A  & B  & C  & 0 \\
      0 & A' & B' & C' & 0 \\ };
  { [start chain] \chainin (m-1-1);
    \chainin (m-1-2);
    { [start branch=A] \chainin (m-2-2)
        [join={node[right] {$\scriptstyle\eta_1$}}];}
    \chainin (m-1-3) [join={node[above]
                      {$\scriptstyle\varphi$}}];
    { [start branch=B] \chainin (m-2-3)
        [join={node[right] {$\scriptstyle\eta_2$}}];}
    \chainin (m-1-4) [join={node[above]
                      {$\scriptstyle\psi$}}];
    { [start branch=C] \chainin (m-2-4)
        [join={node[right] {$\scriptstyle\eta_3$}}];}
    \chainin (m-1-5); }
  { [start chain] \chainin (m-2-1);
    \chainin (m-2-2);
    \chainin (m-2-3) [join={node[above]
                      {$\scriptstyle\varphi'$}}];
    \chainin (m-2-4) [join={node[above]
                      {$\scriptstyle\psi'$}}];
    \chainin (m-2-5); }
\end{tikzpicture}

Output:

See full LaTeX source code.
During writing of this entry I’ve applied that modification also on CQF.info.

If graphics or graphics and text had to be set side-by-side they would often be placed inside minipage environments. This usually works fine if the minipages should be bottom-aligned. A frequently asked question is how to get top alignment, like here on mrunix.de and here on matheplanet.com. A first approach could be to use t as optional positioning argument of the minipage environment. Here’s a compilable example, showing that graphics would stay bottom-aligned that way, used for a fix:

\documentclass{article}
\usepackage[demo]{graphicx}
\begin{document}
\begin{figure}[ht]
  \fbox{\begin{minipage}[t]{150pt}
    \includegraphics[height=100pt,width=150pt]{test}
  \end{minipage}}
  \hfill
  \fbox{\begin{minipage}[t]{150pt}
    \includegraphics[height=60pt,width=150pt]{test}
  \end{minipage}}
\end{figure}
\end{document}

I’ve used \fbox additionally to visualize the minipages. You may notice that it’s compilable even without the image file, that’s achieved by using demo as option for graphicx.

The reason is that \includegraphics sets the baseline to the bottom. A quick fix is just to insert \vspace{0pt} right before each \includegraphics command, this way the reference point will be the top and both images will be placed top-aligned now.

You could use the same approach if you want to place graphics inside \parbox or inside table cells top-aligned.

A question on LaTeX-Community.org inspired me to try pgf/TikZ together with titlesec to produce fancy chapter headings. The result is this small compilable demonstration example:

\documentclass[svgnames]{report}
\usepackage{tikz}
\usepackage{kpfonts}
\usepackage[explicit]{titlesec}
\newcommand*\chapterlabel{}
\titleformat{\chapter}
  {\gdef\chapterlabel{}
   \normalfont\sffamily\Huge\bfseries\scshape}
  {\gdef\chapterlabel{\thechapter\ }}{0pt}
  {\begin{tikzpicture}[remember picture,overlay]
    \node[yshift=-3cm] at (current page.north west)
      {\begin{tikzpicture}[remember picture, overlay]
        \draw[fill=LightSkyBlue] (0,0) rectangle
          (\paperwidth,3cm);
        \node[anchor=east,xshift=.9\paperwidth,rectangle,
              rounded corners=20pt,inner sep=11pt,
              fill=MidnightBlue]
              {\color{white}\chapterlabel#1};
       \end{tikzpicture}
      };
   \end{tikzpicture}
  }
\titlespacing*{\chapter}{0pt}{50pt}{-60pt}
 
\begin{document}
\tableofcontents
\chapter{Introduction}
Text
\chapter{Main}
\section{Section}
Text
\begin{thebibliography}{99}
\bibitem{Test} test reference
\end{thebibliography}
\end{document}

Screenshot:

See also pdf output of this test & demo file.