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+% hp-2019ws-p1.pdf - Labor Notes on Low-Level Programming
+% Copyright (C) 2014, 2015, 2018, 2019 Peter Gerwinski
+%
+% This document is free software: you can redistribute it and/or
+% modify it either under the terms of the Creative Commons
+% Attribution-ShareAlike 3.0 License, or under the terms of the
+% GNU General Public License as published by the Free Software
+% Foundation, either version 3 of the License, or (at your option)
+% any later version.
+%
+% This document is distributed in the hope that it will be useful,
+% but WITHOUT ANY WARRANTY; without even the implied warranty of
+% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+% GNU General Public License for more details.
+%
+% You should have received a copy of the GNU General Public License
+% along with this document. If not, see <http://www.gnu.org/licenses/>.
+%
+% You should have received a copy of the Creative Commons
+% Attribution-ShareAlike 3.0 Unported License along with this
+% document. If not, see <http://creativecommons.org/licenses/>.
+
+% README: Versuch 3, 12. und 19.12.2019: Weltraum-Simulation
+
+\documentclass[a4paper]{article}
+
+\usepackage{pgscript}
+\usepackage{multicol}
+%\usepackage{sfmath}
+
+\sloppy
+\raggedcolumns
+\pagestyle{empty}
+\addtolength{\textheight}{1cm}
+\newcommand{\sep}{~$\cdot$~}
+\newcommand{\mylicense}{CC-by-sa (Version 3.0) oder GNU GPL (Version 3 oder höher)}
+
+\begin{document}
+
+ \makebox(0,0.005)[tl]{\includegraphics[scale=0.72]{logo-hochschule-bochum-cvh-text-v2.pdf}}\hfill
+ \makebox(0,0)[tr]{\includegraphics[scale=0.5]{logo-hochschule-bochum.pdf}}
+ \par\bigskip\bigskip
+ \begin{center}
+ \Large\textbf{Praktikumsversuch 3: Weltraum-Simulation}
+ \par\medskip
+ \normalsize Hardwarenahe Programmierung\sep
+ Wintersemester 2019/20\sep
+ Prof.~Dr.~Peter Gerwinski
+ \end{center}
+
+ Aufgabe: Schreiben Sie ein C-Programm,
+ das die Bahnen von mindestens 3 Massenpunkten unter Einfluß der Gravitation
+ simuliert und in bewegter Grafik darstellt.
+
+ \begin{multicols}{2}
+
+ \begin{itemize}
+ \item
+ Zwei Massenpunkte ("`Himmelskörper"') mit den Massen $m_i$ und $m_j$
+ an den Orten $\vec{r}_i$ und $\vec{r}_j$ ziehen einander an.
+ Diese Kraft heißt Gravitation. Sie hat den Betrag:
+ \begin{equation}
+ |\vec{F}_{ij}| = \frac{m_j\cdot m_i\cdot G}{|\vec{r}_j - \vec{r}_i|^2}
+ \end{equation}
+ Hierbei ist $G$ eine Konstante (Gravitationskonstante).
+ \item
+ Die auf einen Himmelskörper wirkende Gesamtkraft $\vec{F}_i$
+ ergibt sich als Summe der von allen anderen Himmelskörpern herrührenden
+ Gravitationskräfte:
+ \begin{equation}
+ \vec{F}_i = \sum_{j=0,\,j\ne i}^{N - 1} \vec{F}_{ij}
+ \end{equation}
+ \item
+ Die Gravitationskraft beschleunigt jeden Himmelskörper gemäß:
+ \begin{equation}
+ \vec{F_i} = m_i\cdot \vec{a_i}
+ \end{equation}
+ \item
+ Beispiel: Wir betrachten zwei Himmelskörper. Einer davon ("`Zentralgestirn"')
+ ruht im Zentrum ($\vec{r}_0 = 0$, $\vec{v}_0 = 0$)
+ und hat eine wesentlich größere Masse als der andere
+ ("`Satellit"', $m_1 \ll m_0$). Mit geeignetem Anfangsort $\vec{r}_1$
+ und geeigneter Anfangsgeschwindigkeit $\vec{v}_1$ beschreibt dann
+ der Satellit eine elliptische Umlaufbahn um das Zentralgestirn.
+ \item
+ Wir rechnen in zwei Dimensionen $x$ und $y$.
+ \item
+ Für die Zerlegung einer Kraft $\vec{F}_{ij}$ in $x$- und $y$-Komponenten
+ benötigen Sie nur die Grundrechenarten und die Wurzelfunktion,
+ jedoch insbesondere \emph{keine} trigonometrischen Funktionen:
+ \begin{equation}
+ \vec{F}_{ij} = |\vec{F}_{ij}| \cdot \frac{\vec{r}_j - \vec{r}_i}{|\vec{r}_j - \vec{r}_i|}
+ \end{equation}
+ \columnbreak
+ \item
+ Die Wurzelfunktion \lstinline{sqrt()} finden Sie
+ in der Mathematik-Bibliothek.
+ Um diese zu nutzen, verwenden Sie \lstinline{#include <math.h>} im Quelltext,
+ und geben Sie beim \lstinline[style=cmd]{gcc}-Aufruf
+ \lstinline[style=cmd]{-lm} mit an.
+ \item
+ Für die Simulation betrachten wir das System in kurzen Zeitintervallen $dt$
+ und berechnen die Änderungen des Ortes $\vec{r}_i = (x_i,y_i)$
+ und der Geschwindigkeit $\vec{v}_i = (v_{xi},v_{yi})$ jedes Himmelskörpers
+ mit Hilfe des expliziten Eulerschen Polygonzugverfahrens.
+ \par
+ (Wer möchte, darf natürlich auch andere Verfahren anwenden,
+ beispielsweise das klassische Runge-Kutta-Verfahren 4.~Ordnung.)
+ \item
+ Für eine derartige Simulation
+ einschließlich ihrer Darstellung als bewegte Grafik
+ können Sie sich von dem Beispiel-Programm \gitfile{hp}{20191205}{gtk-16.c}
+ inspirieren lassen. (Compilieren mit:
+ \lstinline[style=cmd]{gcc}
+ \lstinline[style=cmd]{-Wall}
+ \lstinline[style=cmd]{-O}
+ \lstinline[style=cmd]{$(pkg-config}
+ \lstinline[style=cmd]{--cflags}
+ \lstinline[style=cmd]{--libs}
+ \lstinline[style=cmd]{gtk+-3.0)}
+ \lstinline[style=cmd]{gtk-16.c}
+ \lstinline[style=cmd]{-o}
+ \lstinline[style=cmd]{gtk-16})
+ \item
+ In einer \file{GTK+}-\lstinline{drawing_area}
+ liegt der Nullpunkt der Zeichnung oben links,
+ eine Längeneinheit entspricht einem Pixel,
+ und die $y$-Koordinate wächst nach unten.
+ Es empfiehlt sich, die Koordinaten so umzurechnen,
+ daß der Nullpunkt in der Mitte der Zeichnung liegt,
+ die Längeneinheit Ihrem persönlichen Geschmack entspricht
+ und die $y$-Koordinate nach oben wächst.
+ \item
+ Beispiel-Szenarien für 3 oder mehr Körper:
+ \vspace{-\smallskipamount}
+ \begin{itemize}\itemsep0pt
+ \item
+ Planet mit Mond umkreist Sonne
+ \item
+ Sonne mit mehreren Planeten, die sich gegenseitig beeinflussen
+ \item
+ zwei Sonnen umkreisen sich gegenseitig, Planet kreist drumherum
+ \item
+ Raumsonde besucht nacheinander mehrere Planeten
+ \end{itemize}
+ \end{itemize}
+
+ \bigskip
+
+ \strut\hfill\emph{Viel Erfolg!}\qquad\qquad
+
+ \end{multicols}
+
+ \vfill
+
+ \begingroup
+
+ \small
+
+ \setlength{\leftskip}{3cm}
+
+ Stand: 10.\ Dezember 2019
+
+% Soweit nicht anders angegeben:\\
+ Copyright \copyright\ 2014, 2015, 2018, 2019\quad Peter Gerwinski\\
+ Lizenz: \mylicense
+
+ Sie können diese Praktikumsunterlagen einschließlich \LaTeX-Quelltext
+% und Beispielprogramme\\
+ herunterladen unter:\\
+ \url{https://gitlab.cvh-server.de/pgerwinski/hp}
+
+ \endgroup
+
+\end{document}
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diff --git a/20191212/pgscript.sty b/20191212/pgscript.sty
new file mode 100644
index 0000000000000000000000000000000000000000..0a36e84e6b3087a3369e74d1a5b33fd58902993d
--- /dev/null
+++ b/20191212/pgscript.sty
@@ -0,0 +1,137 @@
+% pgscript.sty - LaTeX Settings for Lecture Notes
+% Copyright (C) 2012, 2015, 2017, 2018 Peter Gerwinski
+%
+% This document is free software: you can redistribute it and/or
+% modify it either under the terms of the Creative Commons
+% Attribution-ShareAlike 3.0 License, or under the terms of the
+% GNU General Public License as published by the Free Software
+% Foundation, either version 3 of the License, or (at your option)
+% any later version.
+%
+% This document is distributed in the hope that it will be useful,
+% but WITHOUT ANY WARRANTY; without even the implied warranty of
+% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+% GNU General Public License for more details.
+%
+% You should have received a copy of the GNU General Public License
+% along with this document. If not, see <http://www.gnu.org/licenses/>.
+%
+% You should have received a copy of the Creative Commons
+% Attribution-ShareAlike 3.0 Unported License along with this
+% document. If not, see <http://creativecommons.org/licenses/>.
+
+\usepackage{amsfonts}
+\usepackage[colorlinks,allcolors=blue]{hyperref}
+\usepackage[british,german]{babel} % Yes, really "german" and not "ngerman".
+\usepackage[utf8]{luainputenc} % Without this, umlauts are broken. Weird.
+\usepackage{microtype}
+\usepackage[T1]{fontenc}
+\usepackage{times}
+\usepackage{helvet}
+\renewcommand*\familydefault{\sfdefault}
+\usepackage{graphicx}
+\usepackage{ifluatex}
+\usepackage{xcolor}
+\usepackage{enumerate}
+\usepackage{ifthen}
+
+%% Repair kerning: Automatically insert "\kern{-0.15em}" between "//" % (in URLs).
+%% PG20151206: This seems unnecessary here. Maybe due to \sf?
+%\ifluatex
+%\directlua{
+% local glyph = node.id ("glyph")
+% local function my_kerning (head)
+% for t in node.traverse (head) do
+% if t.id == glyph and t.char == 47 then
+% if t.next
+% and t.next.next
+% and t.next.next.id == glyph
+% and t.next.next.char == 47 then
+% local k = node.new ("kern")
+% k.kern = tex.sp ("-0.15em")
+% k.next = t.next
+% k.prev = t
+% t.next.prev = k
+% t.next = k
+% end
+% end
+% end
+% node.kerning (head)
+% end
+% luatexbase.add_to_callback ("kerning", my_kerning, "URL kerning")
+%}
+%\fi
+
+\definecolor{blendedblue}{rgb}{0.2,0.2,0.7}
+\definecolor{darkgreen}{rgb}{0.0,0.3,0.0}
+\definecolor{darkred}{rgb}{0.7,0.0,0.0}
+\definecolor{darkgrey}{rgb}{0.4,0.4,0.4}
+
+\newcommand{\breath}{\bigskip\goodbreak}
+\newcommand{\subsubsubsection}[1]{\breath\par\textbf{#1}\nopagebreak\par}
+\newenvironment{experts}{\color{darkgrey}}{}
+\newenvironment{whiteout}{\definecolor{darkgreen}{rgb}{1.0,1.0,1.0}%
+ \definecolor{darkred}{rgb}{1.0,1.0,1.0}%
+ \color{white}}{}
+\newenvironment{hint}{%
+ \begin{quote}
+ \addtolength{\leftskip}{0.6cm}%
+% \includegraphics[width=1cm]{Zeichen_101_-_Gefahrstelle,_StVO_1970.pdf}
+ \makebox(0,0)[r]{\includegraphics[width=1cm]{Zeichen_101_-_Gefahrstelle,_StVO_1970.pdf}\hspace*{0.5em}}%
+% \hangindent 1.2cm
+% \hangafter 2
+ \bfseries
+% Foobar Foobar Foobar Foobar Foobar Foobar Foobar Foobar
+% Foobar Foobar Foobar Foobar Foobar Foobar Foobar Foobar
+% Foobar Foobar Foobar Foobar Foobar Foobar Foobar Foobar
+% Foobar Foobar Foobar Foobar Foobar Foobar Foobar Foobar
+ \ignorespaces
+}{%
+ \end{quote}
+}
+\urlstyle{sf}
+\newcommand{\file}[1]{{\color{blendedblue}#1}}
+\newcommand{\textarrow}{{\boldmath $\longrightarrow$}}
+\newcommand{\arrowitem}{\item[\textarrow]}
+\newcommand{\newterm}[1]{\emph{\color{darkgreen}#1}}
+
+\newcounter{exercise}
+\newcommand{\exercise}[1]{\addtocounter{exercise}{1}\subsection*{Aufgabe \arabic{exercise}: #1}}
+\newcommand{\solution}{\subsubsection*{Lösung}}
+
+\newcounter{points}
+\newcommand{\points}[1]{\ifthenelse{#1=1}{(1 Punkt)}{(#1 Punkte)}\addtocounter{points}{#1}}
+
+\newcommand{\gitfile}[3]{\href{https://gitlab.cvh-server.de/pgerwinski/#1/raw/master/#2/#3}{\file{#3}}}
+
+\usepackage{listings}
+\lstset{basicstyle=\color{blendedblue},
+ language=C,
+ captionpos=b,
+ gobble=4,
+ xleftmargin=1em,
+ columns=fullflexible,
+ moredelim=**[is][\color{red}]{¡}{¿}}
+\lstdefinestyle{numbered}{xleftmargin=2em,
+ numbers=left,
+ numberstyle=\footnotesize\color{gray}}
+\lstdefinestyle{terminal}{basicstyle=\ttfamily\color{darkgreen},
+ language={},
+ columns=fixed,
+ moredelim=**[is][\color{darkred}]{¡}{¿},
+ moredelim=**[is][\color{blendedblue}]{°}{¿},
+ moredelim=**[is][\sffamily\it\lstset{columns=fullflexible}]{²}{¿}}
+\lstdefinestyle{cmd}{basicstyle=\ttfamily\color{darkred},
+ language={},
+ columns=fixed,
+ moredelim=**[is][\color{darkgreen}]{¡}{¿},
+ moredelim=**[is][\color{blendedblue}]{°}{¿},
+ moredelim=**[is][\sffamily\it\lstset{columns=fullflexible}]{²}{¿}}
+
+\setlength{\textwidth}{16.5cm}
+\setlength{\textheight}{26.0cm}
+\setlength{\hoffset}{-1.5cm}
+\setlength{\voffset}{-3.0cm}
+\setlength{\parindent}{0pt}
+\setlength{\parskip}{\medskipamount}
+\setlength{\unitlength}{1cm}
diff --git a/20191212/pgslides.sty b/20191212/pgslides.sty
new file mode 100644
index 0000000000000000000000000000000000000000..9a019ce99f03d27a17942facc56fe2145f46b6a6
--- /dev/null
+++ b/20191212/pgslides.sty
@@ -0,0 +1,233 @@
+% pgslides.sty - LaTeX Settings for Lecture Slides
+% Copyright (C) 2012, 2013 Peter Gerwinski
+%
+% This document is free software: you can redistribute it and/or
+% modify it either under the terms of the Creative Commons
+% Attribution-ShareAlike 3.0 License, or under the terms of the
+% GNU General Public License as published by the Free Software
+% Foundation, either version 3 of the License, or (at your option)
+% any later version.
+%
+% This document is distributed in the hope that it will be useful,
+% but WITHOUT ANY WARRANTY; without even the implied warranty of
+% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+% GNU General Public License for more details.
+%
+% You should have received a copy of the GNU General Public License
+% along with this document. If not, see <http://www.gnu.org/licenses/>.
+%
+% You should have received a copy of the Creative Commons
+% Attribution-ShareAlike 3.0 Unported License along with this
+% document. If not, see <http://creativecommons.org/licenses/>.
+
+\usepackage{amsfonts}
+\usepackage[british,german]{babel} % Yes, really "german" and not "ngerman".
+\usepackage[utf8]{luainputenc} % Without this, umlauts are broken. Weird.
+\usepackage{microtype}
+\usepackage[T1]{fontenc}
+\usepackage{times}
+\usepackage{helvet}
+\renewcommand*\familydefault{\sfdefault}
+\usepackage{graphicx}
+\usepackage{pstricks}
+
+\hypersetup{colorlinks,allcolors=blue}
+
+%% @@@ Not necessary for slides. Why???
+%% Repair kerning: Automatically insert "\kern{-0.15em}" between "//" % (in URLs).
+%\directlua{
+% local glyph = node.id ("glyph")
+% local function my_kerning (head)
+% for t in node.traverse (head) do
+% if t.id == glyph and t.char == 47 then
+% if t.next
+% and t.next.next
+% and t.next.next.id == glyph
+% and t.next.next.char == 47 then
+% local k = node.new ("kern")
+% k.kern = tex.sp ("-0.15em")
+% k.next = t.next
+% k.prev = t
+% t.next.prev = k
+% t.next = k
+% end
+% end
+% end
+% node.kerning (head)
+% end
+% luatexbase.add_to_callback ("kerning", my_kerning, "URL kerning")
+%}
+
+\usetheme{default}
+\usefonttheme{structurebold}
+\setbeamertemplate{navigation symbols}{}
+\setbeamersize{text margin left = 0.3cm, text margin right = 0.2cm}
+\setbeamertemplate{itemize item}{$\bullet$}
+\setbeamertemplate{itemize subitem}{--}
+\setbeamerfont{itemize/enumerate subbody}{size=\normalsize}
+\setbeamerfont{itemize/enumerate subsubbody}{size=\normalsize}
+\setbeamercolor{footline}{fg=gray}
+
+\newcommand{\sep}{~$\cdot$~}
+
+\newif\ifminimalistic
+\minimalistictrue
+
+\institute[Hochschule Bochum\sep CVH]{%
+ \makebox(0,0.005)[tl]{\includegraphics[scale=0.72]{logo-hochschule-bochum-cvh-text-v2.pdf}}\hfill
+ \makebox(0,0)[tr]{\includegraphics[scale=0.5]{logo-hochschule-bochum.pdf}}%
+}
+
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+ \leavevmode
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+ \rule{0pt}{5.7pt}%
+ \hspace*{8.55pt}\insertinstitute\hspace*{5.7pt}%
+ \raisebox{-30pt}{\rule{0pt}{1pt}}%
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+ \vskip0pt%
+}
+
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+ \setbeamertemplate{footline}{}
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+ \setbeamertemplate{footline}{%
+ \leavevmode
+ \hbox to \textwidth{%
+ \usebeamercolor{footline}%
+ \usebeamerfont{footline}%
+ \ifminimalistic
+ \strut\hfill
+ \else
+ \,\insertshorttitle\sep
+ \insertshortauthor\sep
+ \insertshortinstitute\sep
+ \insertshortdate\hfill
+ \fi
+ \insertframenumber/\inserttotalframenumber
+ %Folie\,\insertframenumber\sep Seite\,\insertpagenumber\,
+ }%
+ \vskip0pt%
+ }
+\fi
+
+\newcommand{\maketitleframe}{%
+ \ifminimalistic
+ \begin{frame}[t,plain]
+ \insertinstitute
+ \par\vfill
+ \begin{center}
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+ \insertdate
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+\newenvironment{experts}{\color{darkgray}}{}
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