tikz-pgf
I guess this is a very simple question, but I couldn't find the answer… How can I define a variable in TikZ? I want to have something like, for example:
\draw[->] (x1,y1)--(x2,y2);
Such that x1,x2,y1,y2 are defined somewhere else and can be changed in order to adjust the picture.
Should be simple, right?
below always sets the anchor to north, so you have to specify the below of = a for node f before specifying the anchor. Otherwise your anchor specification will be overwritten.north west anchor of f should be below a.south west, not below a.south (which is the default).text width does not include the inner sep, which is 0.3333em by default (so there is an additional 0.6666em per box plus 3 times the distance between nodes and we have to subtract the inner sep of the large box).minimum width and text width is redundant, especially if the text width is larger. The complete code is:
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{positioning}
\begin{document}
\begin{tikzpicture}[x=20pt, y=20pt, node distance=1pt,outer sep = 0pt]
\tikzstyle{box}=[rectangle,draw,anchor=north west,text centered, fill=green!20, inner sep=0.3333em]
\tikzstyle{smallbox}=[box,minimum height=20pt,text width=4em]
\tikzstyle{normalbox}=[box,minimum height=20pt,text width={16em + 3*0.6666em + 3pt}]
\tikzstyle{bigbox}=[normalbox,minimum height=40pt]
\node[smallbox] (a) at (1,1) {a};
\node[smallbox] (b) [right = of a] {b};
\node[smallbox] (c) [right = of b] {c};
\node[smallbox] (d) [right = of c] {d};
\node[below = of a.south west, normalbox] (f) {f};
\node[bigbox] (g) [below = of f] {g};
\node[normalbox] (h) [below = of g] {h};
\node[box, right = of d.north east, anchor=north west,text width=4em, minimum height=103pt] (j) {j};
\end{tikzpicture}
\end{document}
The spy TikZ-library was created exactly for this. Here an example. See the PGF/TikZ manual in section 49 Spy Library: Magnifying Parts of Pictures, page 462 for more details.
\documentclass[10pt,letterpaper]{article}
\usepackage[left=1in,right=1in,top=1in,bottom=1in]{geometry}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsthm}
\usepackage[version=0.96]{pgf}
\usepackage{tikz}
\usetikzlibrary{arrows,shapes,automata,backgrounds,petri,positioning}
\usetikzlibrary{decorations.pathmorphing}
\usetikzlibrary{decorations.shapes}
\usetikzlibrary{decorations.text}
\usetikzlibrary{decorations.fractals}
\usetikzlibrary{decorations.footprints}
\usetikzlibrary{shadows}
\usetikzlibrary{calc}
\usetikzlibrary{spy}
\begin{document}
\begin{center}
\begin{tikzpicture}[shorten >=1pt, node distance=3cm, auto, on grid, initial text=,font=\small,>=stealth',
every state/.style={minimum size=7mm,draw=black!50,very thick,fill=red!50},spy using outlines]
\node[state,initial] (S) {S};
\node[state] (A) [right=of S] {A};
\node[state] (B) [below=of S] {B};
\node[state,accepting] (C) [right=of B] {C};
\path[->]
(S) edge[bend right] node{a} (A)
(S) edge[bend right] node[xshift=-4mm]{$\lambda$} (B)
(A) edge[bend right] node[yshift=5mm]{a,b} (S)
(A) edge[] node{$\lambda$} (C)
(A) edge[] node[yshift=7mm]{b} (B)
(B) edge[bend left] node{b, $\lambda$} (C)
(B) edge[bend right] node[xshift=4mm]{a} (S)
(C) edge[bend left] node{a,b} (B)
;
\spy [blue,draw,height=5cm,width=10cm,magnification=2,connect spies] on ($(B)!.5!(C)$) in node at ($(B)!.5!(C) + (0,-5) $);
\end{tikzpicture}
\end{center}
\end{document}
Best Answer
You can add
\newcommand\XA{2}etc. and then\coordinate (A) at (\XA,\YA);