黄金比のシンプルな TikZ 画像を作成するにはどうすればよいでしょうか?

Question

黄金数の起源を説明する短い記事を書きたいのです(1+sqrt(5))/2が、アップロードした画像のような非常にシンプルなセグメントを描く必要があります。何か提案はありますか?

Answer 1

2 つの TikZ の提案。

\documentclass[tikz,border=4mm]{standalone}
\begin{document}

\begin{tikzpicture}
\pgfmathsetmacro\gratio{(1+sqrt(5))/2}
\def\lenB{2}
\path (0,0) node[coordinate](start){} ++(\gratio*\lenB,0)node[coordinate](a){} -- ++(\lenB,0)node[coordinate](b){};

\draw (start) --node[above] {$a$} (a) --node[above]{$b$} (b);

\draw [stealth-stealth] ([yshift=-9pt]start) --node[fill=white,inner ysep=0pt]{$a+b$} ([yshift=-9pt]b);

\foreach \n in {start,a,b}
  \draw (\n) ++(0,-2pt) -- ++(0,4pt);

\end{tikzpicture}
\end{document}

\documentclass[border=4mm,tikz]{standalone}

\usetikzlibrary{decorations.pathreplacing}

\begin{document}

\begin{tikzpicture}[decoration=brace]
\pgfmathsetmacro\gratio{(1+sqrt(5))/2}
\def\lenB{2}
\draw (0,0) node[coordinate](start){} -- ++(\gratio*\lenB,0)node[coordinate](a){} -- ++(\lenB,0)node[coordinate](b){};


\draw [decorate] ([yshift=-4pt]b) --node[below]{$a+b$} ([yshift=-4pt]start);
\draw [decorate] ([yshift=4pt]start) --node[above]{$a$} ([yshift=4pt]a);
\draw [decorate] ([yshift=4pt]a) --node[above]{$b$} ([yshift=4pt]b);

\foreach \n in {start,a,b}
  \draw (\n) ++(0,-2pt) -- ++(0,4pt);

\end{tikzpicture}
\end{document}

Answer 2

飾り気のないプレゼンテーション:

\documentclass{article}
\newlength{\grlen}
% http://www.goldennumber.net/golden-section/
\def\gratio{1.61803}% Roughly
\begin{document}
\[
  \setlength{\grlen}{50pt}% Modify this to your liking
  \underbrace{%
    \overbrace{
      \makebox[0pt][l]{\rule[-1ex]{.4pt}{2.4ex}}
      \makebox[\gratio\grlen]{\hrulefill}
      \makebox[0pt][r]{\rule[-1ex]{.2pt}{2.4ex}}}^a
    \mkern-3mu
    \overbrace{
      \makebox[0pt][l]{\rule[-1ex]{.2pt}{2.4ex}}
      \makebox[\grlen]{\hrulefill}
      \makebox[0pt][r]{\rule[-1ex]{.4pt}{2.4ex}}}^b
  }_{a+b}
\]
\end{document}

Answer 3

2次元表現では、黄金比黄金比を視覚的にわかりやすく表現しています。

\documentclass{article}

\usepackage{tikz}

\begin{document}
\begin{figure}
\centering
\begin{tikzpicture}[scale=3]
  \def\phiGR{1.618034}
    \draw[thick,red,dashed] (0,0) rectangle (\phiGR,1);
    \draw[thick,black,dotted] (\phiGR,0) rectangle (1,1);
    \draw (0,0.5) node[left] {\(a\)};
    \draw (0.5,0) node[below] {\(a\)};
    \draw ({.5*(1+\phiGR)},0) node[below] {\(b\)};  
\end{tikzpicture}
\end{figure}

\emph{Scale similarity} is a nice property of the golden ratio.
This property is well illustrated by a \emph{golden rectangle},
whose sides, \(a\)~and~\(a+b\) (where~\(a>b\)), are such that
%
\[
  \frac{a}{a+b} = \frac{b}{a} \,.
\]
%
The red dashed and black dotted rectangles are \emph{similar},
i.e.\ one is a scaled version of the other.
You can show (left as an exercise!) that
%
\[
  \frac{a+b}{a} = \frac{\sqrt{5}+1}{2} \approx 1.618034 \,.
\]
%
That quantity is called the \emph{golden ratio} and usually denoted by~\(\phi\).
\end{document}

Answer 4

PSTricks を使ったタイピング練習にはいつも短すぎます。

\documentclass[pstricks,12pt]{standalone}
\usepackage{pst-node}
\begin{document}
\begin{pspicture}[arrows=|*-|*,shortput=nab](8,2)
    \pcline(1,1)(5,1)^{$a$}
    \pcline(5,1)(7,1)^{$b$}
    \pcline[offset=-.5]{<->}(1,1)(7,1)\ncput*{$a+b$}
\end{pspicture}
\end{document}