added neighborhood topology example

tikz/neighbourhood-topology/Makefile

@@ -0,0 +1,31 @@
+SOURCE = neighbourhood-topology
+DELAY = 80
+DENSITY = 300
+WIDTH = 512
+
+make:
+	pdflatex $(SOURCE).tex -output-format=pdf
+	make clean
+
+clean:
+	rm -rf  $(TARGET) *.class *.html *.log *.aux *.data *.gnuplot
+
+gif:
+	pdfcrop $(SOURCE).pdf
+	convert -verbose -delay $(DELAY) -loop 0 -density $(DENSITY) $(SOURCE)-crop.pdf $(SOURCE).gif
+	make clean
+
+png:
+	make
+	make svg
+	inkscape $(SOURCE).svg -w $(WIDTH) --export-png=$(SOURCE).png
+
+transparentGif:
+	convert $(SOURCE).pdf -transparent white result.gif
+	make clean
+
+svg:
+	#inkscape $(SOURCE).pdf --export-plain-svg=$(SOURCE).svg
+	pdf2svg $(SOURCE).pdf $(SOURCE).svg
+	# Necessary, as pdf2svg does not always create valid svgs:
+	inkscape $(SOURCE).svg --export-plain-svg=$(SOURCE).svg

tikz/neighbourhood-topology/Readme.md

@@ -0,0 +1,3 @@
+Compiled example
+----------------
+![Example](neighbourhood-topology.png)

tikz/neighbourhood-topology/neighbourhood-topology.tex

@@ -0,0 +1,53 @@
+\documentclass[varwidth=true, border=2pt]{standalone}
+\usepackage{tikz}
+\usepackage{pgfplots}
+
+\begin{document}
+\begin{tikzpicture}[>=stealth,]
+    \begin{axis}[
+        axis x line=middle,
+        axis y line=middle,
+        %width=9cm,
+        %height=4.5cm,
+        xmin=-1,     % start the diagram at this x-coordinate
+        xmax= 5,    % end   the diagram at this x-coordinate
+        ymin=-1,     % start the diagram at this y-coordinate
+        ymax= 5,   % end   the diagram at this y-coordinate
+        xlabel=$X_1$,
+        ylabel=$X_2$,
+        ticks=none,
+        enlargelimits=true,
+        after end axis/.code={
+            \draw [decorate,decoration={brace,mirror,raise=15pt}] (axis cs:0,3.6) -- (axis cs:0,2.5) node [midway,left=20pt] {$U_2$};
+            \draw [decorate,decoration={brace,mirror,raise=12pt}] (axis cs:1.5,0) -- (axis cs:2.5,0) node [midway,below=16pt] {$U_1$};
+        }]
+
+        \addplot[mark=none, orange, smooth, thick, fill=orange!30] coordinates {(1,1) (2,0.5) (3,1.5) (3,2) (3.5,3) (3.2, 5) (2.2, 4.7) (1.5, 4.2) (1.1, 3.9) (0.9, 2.5) (1,1)};
+        \node[orange] at (axis cs:4,4) [anchor=south] {$U$};
+
+        % Draw help lines
+        \addplot[dashed] coordinates {(1.5,0) (1.5,3.6)};
+        \addplot[dashed] coordinates {(2.5,0) (2.5,3.6)};
+        \addplot[dashed] coordinates {(0,2.5) (2.5,2.5)};
+        \addplot[dashed] coordinates {(0,3.6) (2.5,3.6)};
+
+        % Draw solid square
+        \addplot[mark=none, red, thick, fill=red!30] coordinates {(2.5,2.5) (2.5,3.6) (1.5,3.6) (1.5,2.5) (2.5,2.5)};
+
+        % Draw x and annotation
+        \node[blue] at (axis cs:2,3) [anchor=south west] {$x$};
+        \addplot[mark=*, blue] coordinates {(2,3)};
+
+        % Draw ticks of help lines
+        \addplot[mark=none, red, thick] coordinates {(1.5, -0.1) (1.5,0.1)};
+        \addplot[mark=none, red, thick] coordinates {(2.5, -0.1) (2.5,0.1)};
+        \addplot[mark=none, red, thick] coordinates {(-0.1, 2.5) (0.1,2.5)};
+        \addplot[mark=none, red, thick] coordinates {(-0.1, 3.6) (0.1,3.6)};
+
+        % Draw axis text
+        \node[blue] at (axis cs:0,3) [anchor=east] {$x_2$};
+        \node[blue] at (axis cs:2,0) [anchor=north] {$x_1$};
+
+    \end{axis} 
+\end{tikzpicture}
+\end{document}