diff --git a/tex/content/figures/part01/ch1/sum_odd_numbers_to_square.fig.pdf b/tex/content/figures/part01/ch1/sum_odd_numbers_to_square.fig.pdf
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+
+
diff --git a/tex/content/figures/part01/ch1/sum_odd_numbers_to_square.fig.tex b/tex/content/figures/part01/ch1/sum_odd_numbers_to_square.fig.tex
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+\documentclass{article}
+
+\usepackage{graphicx}
+\usepackage{caption}
+
+\begin{document}
+\begin{figure}
+ \centering
+ \includegraphics[scale=1]{sum_odd_numbers_to_square}
+ \setcounter{figure}{2}
+ \caption{The sum of odd numbers is a square}
+\end{figure}
+\end{document}
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+
+
diff --git a/tex/content/figures/part01/ch1/sum_odd_numbers_to_square.tex b/tex/content/figures/part01/ch1/sum_odd_numbers_to_square.tex
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+% Draw a 6 by 6 grid of squares, with thicker line on outer borders.
+
+\documentclass[margin=0.5cm]{standalone}
+
+\usepackage{tikz}
+\usetikzlibrary{calc}
+
+\begin{document}
+
+\begin{tikzpicture}
+ % Draw grid
+ \draw (0, 0) grid (6, 6);
+ % Draw thicker lines on outer borders
+ \draw[thick] (0, 0) -- (6, 0) -- (6, 6) -- (0, 6) -- (0, 0);
+
+ % Draw for each square with bottom left corner at (0, 0) to (6, 6) the thicker border
+ \foreach \i in {0, 1, 2, 3, 4, 5, 6}
+ \draw[very thick] (0, 0) -- (\i, 0) -- (\i, \i) -- (0, \i) -- (0, 0);
+
+ % For each $i$-th odd number from 1 to 11, add a node at the top right corner of the $i$-th square
+ \foreach \i [evaluate={\x=int(\i*2+1);}] in {0, 1, 2, 3, 4, 5}
+ \node at (\i+0.5, \i+0.5) {$\x$};
+\end{tikzpicture}
+
+\end{document}
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diff --git a/tex/definitions.tex b/tex/definitions.tex
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diff --git a/tex/preamble.tex b/tex/preamble.tex
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@@ -10,7 +10,6 @@
}
% Create a new environment {exercise} to refer to exercises from the KNUTH book.
-% Add a TODO switch option to show unresolved exercises
\newenvironment{myexercise}[2]
{
\addcontentsline{toc}{subsubsection}{Exercise #1}