[Tex/LaTex] Compilation problem with tikz diagram

compilingmatricestikz-matrixtikz-pgf

As I said, I'm writing math books for school; one of them is about matrices and I have several problems with it.

It's a big code, so I'm trying to summarize it:

Problem with TikZ matrix:
When I try to compile it something like

\draw [<->, yl] (A-2-4.north) to [bend left] node [arrow style mul] {$+$} (B-2-4.north);

using the tikz package and the following tikz libraries:

\usepackage{tikz}
\usetikzlibrary{decorations.pathmorphing}
\usetikzlibrary{decorations.markings}
\usetikzlibrary{shapes,snakes,calc,arrows}
\usetikzlibrary{intersections,through,backgrounds}
\usetikzlibrary{shapes.arrows,chains,positioning}
\usetikzlibrary{matrix,decorations.pathmorphing}

I get

No shaped name A-2-4 is known. See the pgf package documentation for explanation

And when I try to compile this (using \include{filename}):

 \chapterimage{m2summary.pdf}
 \chapter{Respostas e soluções}
 \begin{multicols}{2}
 \section*{\textcolor{ocre}{1. Matrizes}}
 \subsection*{Exercícios de fixação}
 \begin{enumerate}[label=\arabic*.]
 \tiny{
 \item $\ds A=\begin{bmatrix} 0 & -1 & -2 \\ 1 & 0 & -1 \\ 2 & 1 & 0 \end{bmatrix}$
 }
 \end{enumerate}
 \end{multicols}

it shows:

Missing $ inserted. HOW? I tried to compile with no text, actually, with no math text, and it keeps showing that $ is missing. I really don't know what to do!

Sorry for making this long post, I just tried to be as complete as I can. And I use WinEdt 8, MikTeX 2.9 that I installed this week (February 2014).

Code of TIKZ pic:

\begin{tikzpicture}
\matrix(A)[matrix of math nodes, nodes={node style ge}, left delimiter={[}, right delimiter={]}] at (0,0){
  a_{11}                         & a_{12}                         & \cdots & a_{1n}                         \\
  \node[node style sp] {a_{21}}; & \node[node style sp] {a_{22}}; & \cdots & \node[node style sp] {a_{2n}}; \\
  \vdots                         & \vdots                         & \ddots & \vdots                         \\
  a_{m1}                         & a_{m2}                         & \cdots & a_{mn}                         \\
};
\node [draw, above=10pt] at (A.north) {matriz $\color{ocre}A$};
\node [right=20pt] at (A.east) {$\color{ocre}+$};

\matrix(B)[matrix of math nodes, nodes={node style ge}, left delimiter={[}, right delimiter={]}] at (6,0){
  b_{11}                         & b_{12}                         & \cdots & b_{1n}                         \\
  \node[node style sp] {b_{21}}; & \node[node style sp] {b_{22}}; & \cdots & \node[node style sp] {b_{2n}}; \\
  \vdots                         & \vdots                         & \ddots & \vdots                         \\
  b_{m1}                         & b_{m2}                         & \cdots & b_{mn}                         \\
};
\node [draw, above=10pt] at (B.north) {matriz $\color{ocre}B$};

\matrix(C)[matrix of math nodes, nodes={node style ge}, left delimiter={[}, right delimiter={]}] at (6,-4.5){
  c_{11}                              & c_{12}                               & \cdots & c_{1n}                                \\
  \node[node style sp, ocre] {c_{21}}; & \node[node style sp, blue] {c_{22}}; & \cdots & \node[node style sp, yl] {c_{2n}}; \\
  \vdots                              & \vdots                               & \ddots & \vdots                                \\
  c_{m1}                              & c_{m2}                               & \cdots & c_{mn}                                \\
};
\node [draw, below=10pt] at (C.south) {matriz $\color{ocre}C=A+B$};

\node (a) [above=10pt] at (A-2-1.north) {};
\node (b) [above=10pt] at (C-2-1.north) {};

\draw [<->, yl] (A-2-4.north) to [bend left] node [arrow style mul] {$+$} (B-2-4.north);
\draw [->, yl] (B-2-4.south) to (C-2-4.north);

\draw [<->, blue] (A-2-2.north) to [bend left] node [arrow style mul] {$+$} (B-2-2.north);
\draw [->, blue] (B-2-2.south) to (C-2-2.north);

\draw [<->, ocre] (A-2-1.north) to [bend left] node [arrow style mul] {$+$} (B-2-1.north);
\draw [->, ocre] (B-2-1.south) to (C-2-1.north);
\end{tikzpicture}

Best Answer

(This answers only the TikZ question. For the other, I'd recommend reducing your code to a minimal working example (MWE) and asking a new question about that.)

Your problem is that you have a matrix of math nodes, but you're using \node {} in the cells. By default, when you have a matrix of (math) nodes TikZ prepends something like \node [name=A-1-2] { to the contents of the cell (and adds the closing }; after), but not when you use \node or similar in a cell. Quoting the manual:

Conceptually, this key adds \node{ at the beginning and }; at the end of each cell and sets the anchor of the node to base. Furthermore, it adds the option name option to each node, where the name is set to matrix name - row number - column number. For example, if the matrix has the name my matrix, then the node in the upper left cell will get the name my matrix-1-1.

[..]

If your cell starts with a \path command or any command that expands to \path, which includes \draw, \node, \fill and others, the \node{ startup code and the }; code are suppressed.

To be able to pass options/styles to the nodes, write e.g.

|[my node style]| content of matrix cell

I.e. add vertical bars around the brackets containing the options, and place this at the beginning of the cell.

Complete code below. You didn't add the definition of your styles, so I defined them as empty styles.

enter image description here

\documentclass[11pt]{standalone}
\usepackage{tikz}
\usetikzlibrary{matrix}

\tikzset{
  node style ge/.style={},
  node style sp/.style={},
  yl/.style={},
  arrow style mul/.style={},
}
\definecolor{ocre}{RGB}{204, 119, 34}
\begin{document}

\begin{tikzpicture}
\matrix(A)[matrix of math nodes, nodes={node style ge}, left delimiter={[}, right delimiter={]}] at (0,0){
  a_{11}                         & a_{12}                         & \cdots & a_{1n}                         \\
 | [node style sp]| a_{21} & |[node style sp]| a_{22} & \cdots & |[node style sp]| a_{2n} \\
  \vdots                         & \vdots                         & \ddots & \vdots                         \\
  a_{m1}                         & a_{m2}                         & \cdots & a_{mn}                         \\
};
\node [draw, above=10pt,font=\color{ocre}] at (A.north) {matriz $A$};
\node [right=20pt,font=\color{ocre}] at (A.east) {$+$};

\matrix(B)[matrix of math nodes, nodes={node style ge}, left delimiter={[}, right delimiter={]}] at (6,0){
  b_{11}                         & b_{12}                         & \cdots & b_{1n}                         \\
  |[node style sp]| b_{21} & |[node style sp]| b_{22} & \cdots & |[node style sp]| b_{2n} \\
  \vdots                         & \vdots                         & \ddots & \vdots                         \\
  b_{m1}                         & b_{m2}                         & \cdots & b_{mn}                         \\
};
\node [draw, above=10pt,font=\color{ocre}] at (B.north) {matriz $B$};

\matrix(C)[matrix of math nodes, nodes={node style ge}, left delimiter={[}, right delimiter={]}] at (6,-4.5){
  c_{11}                              & c_{12}                               & \cdots & c_{1n}                                \\
  |[node style sp,ocre]| c_{21} & |[node style sp, blue]| c_{22} & \cdots & |[node style sp, yl]| c_{2n} \\
  \vdots                              & \vdots                               & \ddots & \vdots                                \\
  c_{m1}                              & c_{m2}                               & \cdots & c_{mn}                                \\
};
\node [draw, below=10pt,font=\color{ocre}] at (C.south) {matriz $C=A+B$};

\node (a) [above=10pt] at (A-2-1.north) {};
\node (b) [above=10pt] at (C-2-1.north) {};

\draw [<->, yl] (A-2-4.north) to [bend left] node [arrow style mul] {$+$} (B-2-4.north);
\draw [->, yl] (B-2-4.south) to (C-2-4.north);

\draw [<->, blue] (A-2-2.north) to [bend left] node [arrow style mul] {$+$} (B-2-2.north);
\draw [->, blue] (B-2-2.south) to (C-2-2.north);

\draw [<->] (A-2-1.north) to [bend left] node [arrow style mul] {$+$} (B-2-1.north);
\draw [->] (B-2-1.south) to (C-2-1.north);
\end{tikzpicture}
\end{document}

Related Solutions

[Tex/LaTex] Rotate a node but not its content: the case of the ellipse decoration

The source of the difficulty is that ellipses are constructed in a particular way in TikZ. They are paths that start from the x-axis and proceed counter-clockwise around their centre. The vast majority of the time, the exact parametrisation doesn't matter. You appear to have found the one situation where it does!

In the actual question, you only want to be able to mirror the ellipse, and so draw it starting from the negative x-axis (the title of the question suggests a more flexible approach). That's actually not too hard since we can exploit the symmetry of the ellipse. The key is to provide it with a negative x-radius, since then it will start from the negative x-axis (and proceed clockwise, but we could correct for that by negating the y-radius as well). To do this, we interrupt the call from the node shape to the drawing command and flip the sign of the x-radius. The simplest way to do this is to redefine the \pgfpathellipse macro to do the negation and then call the original macro. The following code does this.

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{decorations,shapes,decorations.markings}
\makeatletter
\let\origpgfpathellipse=\pgfpathellipse
\def\revpgfpathellipse#1#2#3{%
  #2%
  \pgf@xa=-\pgf@x
  \origpgfpathellipse{#1}{\pgfqpoint{\pgf@xa}{0pt}}{#3}}
\makeatother

\tikzset{
  reversed ellipse/.style={
    ellipse,
    reverse the ellipse%
  },
  reverse the ellipse/.code={
    \let\pgfpathellipse=\revpgfpathellipse
  }
}
\begin{document}
\begin{tikzpicture}
\node[ellipse,
  draw,
  postaction={
    decorate,
    decoration={
      markings,
      mark=at position 1 with {
        \arrow[line width=5pt,blue]{>}
      }
    }
  }
] at (0,0) {hello world};

\node[reversed ellipse,
  draw,
  postaction={
    decorate,
    decoration={
      markings,
      mark=at position 1 with {
        \arrow[line width=5pt,blue]{>}
      }
    }
  }
] at (0,-2) {hello world};
\end{tikzpicture}

\end{document}

Here's the result:

rotated ellipse

(the arrow got clipped, but you can see where it lies)

[Tex/LaTex] Drawing rectilinear curves in Tikz, aka an Etch-a-Sketch drawing

\draw (20,12) -- ++(2,0) -- ++(0,2) -- ++(-3,0) -- ++(45:3);

Use ++ before each new incremental coordinate to make it relative to the last one and put the pencil there.

Here's a complete example:

\documentclass{article}
\usepackage{tikz}
\begin{document}
\tikz\draw (20,12) -- ++(2,0) -- ++(0,2) -- ++(-3,0) -- ++(30:3) {[rounded corners=10pt]-- ++(5,0) -- ++(0,-6)} -- ++(-7,0) -- cycle;
\end{document}

Of course, combining this with the -| or |- path operators can simplify the code even further; the following two pieces of code produce the same result:

\tikz\draw (20,12) -- ++(2,0) -- ++(0,2) -- ++(3,0) -- ++(0,1) -- ++(1,0) -- ++(0,-3) -- ++(2,0);\par\bigskip

and

\tikz\draw (20,12) -| ++(2,2) -| ++(3,1) -- ++(1,0) |- ++(2,-3);

I don't think that defining commands in this case adds anything; in fact, I think it reduces the functionality of the existing syntax (which is already simple). The example demonstrates that you can use, for example, polar coordinates and modify (up to TikZ limitations) the path attributes midways; even if the current question doesn't require this, it's a good thing to have the possibility to do those kind of modification if they are required.

Best Answer

Related Solutions

[Tex/LaTex] Rotate a node but not its content: the case of the ellipse decoration

[Tex/LaTex] Drawing rectilinear curves in Tikz, aka an Etch-a-Sketch drawing

Related Question