122 lines
5.2 KiB
TeX
122 lines
5.2 KiB
TeX
\documentclass[12pt,a4paper,pdftex]{exam}
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\usepackage[german]{babel}
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\usepackage{natbib}
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\usepackage{graphicx}
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\usepackage[small]{caption}
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\usepackage{sidecap}
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\usepackage{pslatex}
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\usepackage{amsmath}
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\usepackage{amssymb}
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\setlength{\marginparwidth}{2cm}
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\usepackage[breaklinks=true,bookmarks=true,bookmarksopen=true,pdfpagemode=UseNone,pdfstartview=FitH,colorlinks=true,citecolor=blue]{hyperref}
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%%%%% text size %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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\usepackage[left=20mm,right=20mm,top=25mm,bottom=25mm]{geometry}
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\pagestyle{headandfoot}
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\header{{\bfseries\large Exercise 4}}{{\bfseries\large Control Flow}}{{\bfseries\large 30. October, 2017}}
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\firstpagefooter{Dr. Jan Grewe}{Phone: 29 74588}{Email:
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jan.grewe@uni-tuebingen.de}
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\runningfooter{}{\thepage}{}
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\setlength{\baselineskip}{15pt}
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\setlength{\parindent}{0.0cm}
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\setlength{\parskip}{0.3cm}
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\renewcommand{\baselinestretch}{1.15}
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\newcommand{\code}[1]{\texttt{#1}}
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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\begin{document}
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\vspace*{-6.5ex}
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\begin{center}
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\textbf{\Large Introduction to scientific computing}\\[1ex]
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{\large Jan Grewe, Jan Benda}\\[-3ex]
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Abteilung Neuroethologie \hfill --- \hfill Institut f\"ur Neurobiologie \hfill --- \hfill \includegraphics[width=0.28\textwidth]{UT_WBMW_Black_RGB} \\
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\end{center}
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The exercises are meant for self-monitoring, revision of the lecture
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topic. You should try to solve them on your own. Your solution should
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be submitted as a single script (m-file) in the Ilias system. Each
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task should be solved in its own ``cell''. Each cell must be
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executable on its own. The file should be named according to the following pattern:
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``variables\_datatypes\_\{lastname\}.m'' benannt werden
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(e.g. variables\_datentypes\_mueller.m).
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\begin{questions}
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\question Implement \code{for} loops in which the \emph{running variable}:
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\begin{parts}
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\part ... assumes values from 0 to 10. Print the value of the running variable for each iteration step.
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\part ... assumes values from 10 to 0. Print out the value for each iteration.
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\part ... assumes values from 0 to 1 in steps of 0.1. Print out the value for each iteration.
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\end{parts}
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\question Indexing in vectros:
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\begin{parts}
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\part Define a vector \code{x} that contains values from 1:100.
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\part Use a \code{for} loop to print each element of \code{x}. Use the running variable for the indexing.
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\begin{solution}
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\code{for i = 1:length(x); disp(x(i)); end}
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\end{solution}
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\part Do the same without using the running variable for indexing.
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\begin{solution}
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\code{for i : x; disp(i); end;}
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\end{solution}
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\end{parts}
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\question Create a vector \verb+x+ that contains 50 random numbers in the range 0 - 10.
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\begin{parts}
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\part Use a loop to calculate the arithmetic mean. The mean is defined as:
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$\overline{x}=\frac{1}{n}\sum\limits_{i=0}^{n}x_i $.
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\part Use a loop to estimate the stadard deviation:
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$\sigma=\sqrt{\frac{1}{n}\sum\limits_{i=0}^{n}(x_i-\overline{x})^2}$).
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\part Search the MATLAB help for functions that do the calculations for you :-).
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\end{parts}
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\question Implement a\code{while} loop
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\begin{parts}
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\part ... that iterates 100 times. Print out the current iteration number.
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\part ... iterates endlessly. You can interrupt the execution with the command \code{Strg + C}.
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\end{parts}
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\question Use an endless \code{while} loop to individually print out the elements of a vector that contains 10 elements.
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\question Use the endless \verb+while+ loop to draw random numbers
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(\verb+randn+) until you it is larger than 1.33.
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\begin{parts}
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\part Count the number of required iterations.
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\part Use a \code{for} loop to run the previous test 1000 times. Remeber all counts and calculate the mean of it.
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\part Create a plot that schows for each of the 1000 trials, how often you had to draw.
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\part Play around with the threshold. What happens?
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\end{parts}
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\question Create a vector \verb+x+ that contains 10 random numbers in the range 0:10.
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\begin{parts}
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\part Use a \code{for} loop to delete all those elements
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(\code{x(index) = [];}) that are smaller than 5.
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\part Delete all elements that are smaller than 5 and larger than 2.
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\part Can you do the same without a loop?
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\end{parts}
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\question Test the random number generator! To do so count the
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number of elements that fall in the classes defined by the edges
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[0.0, 0.2, 0.4, 0.6, 0.8, 1.0]. Store the results in a vector. Use a
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loop to draw 1000 random numbers with \verb+rand()+ (see help). What
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would be the expectation? What is the result?
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\question String parsing: It is quite common to use the names of datasets to encode the conditions under which they were recorded. To find out the required information we have to \emph{parse} he name.
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\begin{parts}
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\part Create a variable
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\verb+filename = '2015-10-12_100Hz_1.25V.dat'+. Obviously, the
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underscore was used as a delimiter.
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\part Use a \verb+for+ loop to find the positions of the underscores and store these in a vector.
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\part Use a second loop to iterate over the previously filled `position' vector and use this information to
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cut filename appropriately.
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\part Print out the individual parts.
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\end{parts}
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\end{questions}
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\end{document}
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