# How to draw infinite earring with TikZ?

I want to draw an infinite earring, i.e., each circle centerd at $(\frac{1}{n},0)$ with radius $\frac{1}{n}$ for each $n\in \mathbf{N}$. The figure will be the following:

I have used the following code to do the diagram:

\documentclass[10pt]{article}
\usepackage{pgf,tikz}
\begin{document}

\begin{tikzpicture}
\foreach \n in {1,2,3,4,5,6,7,...................}
\draw (1/\n,0) circle (1/\n);
\foreach \n in {1,2,3,4,5,6,7,...................}
\draw[fill] (1\n,0) circle (0.5pt);
\end{tikzpictute}
\end{document}


But it shows an error.

• You don't need pgf and it is \end{tikzpicture} – touhami Feb 28 '15 at 8:35

May be better than infinity you fix a large number

 \documentclass{article}
\usepackage{tikz}
\begin{document}

\begin{tikzpicture}
\foreach \n in {1,2,...,2000}
\draw (1/\n,0) circle (1/\n);
\end{tikzpicture}
\end{document}


Edit: we can replace

  \foreach \n in {1,2,...,2000}


by

  \foreach \n in {1,...,2000}


since the step is 1

• {1,...,140} is enough and it makes it much quicker. – LaRiFaRi Jul 8 '15 at 13:34

Couldn't resist to add a MetaPost version of this.

\documentclass{standalone}
\usepackage{luamplib}
\begin{document}
\begin{mplibcode}
r = 10cm; % Unit
d = 2r;
beginfig(1);
for n = 1 upto 1000: draw fullcircle scaled (d/n) shifted (r/n, 0) ; endfor
endfig;
\end{mplibcode}
\end{document}


To be run with LuaLaTeX.

• Surely you meant to write for n=1 upto infinity: (since you can in MP)! – Thruston Feb 28 '15 at 11:45
• @Thruston What's the limiting factor in that case? Don't want to keep compiling until off to the nursing home I go! – 1010011010 Feb 28 '15 at 11:54
• @Thruston I usually use MetaPost with the double numbersystem, and I lose the habit to use the infinity constant, since I thought that infinity would have a much bigger value than 2^12-1. But I must correct myself: infinity is still equal to 2^12-1=4095,99998… in double mode, despite the fact that MetaPost can handle much bigger numerics then; I've just checked it. It looks like an oversight from MetaPost's developers. – Franck Pastor Feb 28 '15 at 12:49
• @1010011010 I was just making an in-joke: one of the amusing features of Metafont/Metapost is that it actually defines a constant infinity. An example of Knuth's humour I think, but occasionally it is useful; for example if you have a path p then point infinity of p is always at the far end of p. – Thruston Feb 28 '15 at 13:41
• If you wonder why I've drawn up to 1000 circles, it is because I wanted to make the white point (the last circle), which is left at the origin in most of the other pictures, completely disappear (in appearance I mean). I first try with n = 100, and it was still here. So I went for n = 1000… I confess, I was too lazy to search a more optimal value for n :-) – Franck Pastor Feb 28 '15 at 16:07

Another solution leveraging nodes' alignment property:

\documentclass[tikz,border=10pt]{standalone}

\pgfkeys{tikz/.cd,
num of circles/.store in=\numcirc,
num of circles=100,
circle initial size/.store in=\circlesize,
circle initial size=3cm,
}
\begin{document}
\begin{tikzpicture}
\foreach \n in {1,...,\numcirc}{
\pgfmathsetmacro\actualsize{\circlesize/\n}
\node[anchor=west,circle,draw,inner sep=\actualsize pt] at (0,0){};
}
\end{tikzpicture}
\end{document}


The result:

• Watch out for the tiny white dot just to the right of the centers of the circles. – Benjamin McKay Mar 1 '15 at 13:45
• @BenjaminMcKay: That's due to the low number of samples used. Just add \begin{tikzpicture}[num of circles=2000] and it will disappear. – Claudio Fiandrino Mar 1 '15 at 13:57

A PSTricks solution:

\documentclass{article}

\usepackage{multido}
\usepackage{pstricks}
\usepackage{xfp}

% parameters
\def\circles{100}

\begin{document}

\end{pspicture}

\end{document}


...and in case the drawing of the circle perimeters are done with a too thick pen:

\documentclass{article}

\usepackage{multido}
\usepackage{pstricks}
\usepackage{xfp}

% parameters
\def\circles{100}