Quero colocar coordenadas nos pontos médios de dois lados da caixa delimitadora de um diagrama contido em uma \piccaixa. Estou planejando ter quatro diagramas semelhantes em quatro quadrantes e quero desenhar setas entre as \piccaixas. Posso citar essas coordenadas ao localizar as caudas das duas setas emanadas do diagrama atual, que estariam posicionadas no quadrante noroeste. Por que recebo um erro com os seguintes comandos?
\path coordinate (midpoint_of_southern_side_of_original_forest) at (current bounding box.south);
\path coordinate (midpoint_of_eastern_side_of_original_forest) at (current bounding box.east);
Coloquei um %na frente desses comandos no código a seguir para que ele seja compilado.
\documentclass[10pt]{amsart}
\usepackage{mathtools,array}
\usepackage{tikz}
\usetikzlibrary{calc,intersections,arrows.meta,bending}
\usepackage{pgfplots}
\pgfplotsset{compat=1.11}
\begin{document}
\noindent \hspace*{\fill}
\begin{tikzpicture}[nodes={inner sep=0, font=\scriptsize,
execute at begin node={\setlength\abovedisplayskip{0.75ex}%
\setlength\belowdisplayskip{0.5ex}%
\setlength\abovedisplayshortskip{0.75ex}%
\setlength\belowdisplayshortskip{0.5ex}}},
shorten/.style={shorten >=#1,shorten <=#1},
pics/fpic/.style={code={#1}}, x=0.75cm, y=0.75cm]
%A forest with a vertex P is drawn.
\matrix[row sep=4.5em, column sep=4.5em]{\pic{fpic={
\path (0,0) coordinate (P)
(240:2) coordinate (v1) ($(v1) +(-0.75,0)$) coordinate (v2) ($(v1) +(260:0.75)$) coordinate (v3)
(0,-2.5) coordinate (v4)
($(v4) +(250:1.75)$) coordinate (v5) ($(v5) +(210:1.5)$) coordinate (v6) ($(v4) +(350:1.75)$) coordinate (v7) ($(v7) +(260:1.75)$) coordinate (v8)
(2,0) coordinate (v9) ($(v9) +(45:0.75)$) coordinate (v10) ($(v9) +(285:0.75)$) coordinate (v11);
\path node[anchor=south] at ($(P) +(0,0.15)$){$P$};
\draw[fill] (P) circle (1.5pt);
\draw[fill] (v1) circle (1.5pt);
\draw[fill] (v2) circle (1.5pt);
\draw[fill] (v3) circle (1.5pt);
\draw[fill] (v4) circle (1.5pt);
\draw[fill] (v5) circle (1.5pt);
\draw[fill] (v6) circle (1.5pt);
\draw[fill] (v7) circle (1.5pt);
\draw[fill] (v8) circle (1.5pt);
\draw[fill] (v9) circle (1.5pt);
\draw[fill] (v10) circle (1.5pt);
\draw[fill] (v11) circle (1.5pt);
\draw (P) -- (v1) -- (v2);
\draw (v1) -- (v2);
\draw (v1) -- (v3);
\draw (P) -- (v4) -- (v5) -- (v6);
\draw (v4) -- (v7) -- (v8);
\draw (P) -- (v9) -- (v10);
\draw (v9) -- (v11);
}}; \\
%\path coordinate (midpoint_of_southern_side_of_original_forest) at (current bounding box.south);
%\path coordinate (midpoint_of_eastern_side_of_original_forest) at (current bounding box.east);
};
%
%
\end{tikzpicture}
\hspace{\fill}
\end{document}