From b67ceae7811ce8e121d84ec10c39599c75ee295c Mon Sep 17 00:00:00 2001
From: Jan Grewe <jan.grewe@g-node.org>
Date: Mon, 9 Nov 2020 22:03:14 +0100
Subject: [PATCH] [programming] add box about colon operator

---
 header.tex                          |  2 +-
 programming/lecture/programming.tex | 15 +++++++++++++--
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/header.tex b/header.tex
index 6511f0a..29f6ba8 100644
--- a/header.tex
+++ b/header.tex
@@ -5,7 +5,7 @@
 \author{{\LARGE Jan Grewe \& Jan Benda}\\[5ex]Abteilung Neuroethologie\\[2ex]%
         \includegraphics[width=0.3\textwidth]{UT_WBMW_Rot_RGB}\vspace{3ex}}
 
-\date{WS 2019/2020\\\vfill%
+\date{WS 2020/2021\\\vfill%
       \centerline{\includegraphics[width=0.7\textwidth]{announcements/correlationcartoon}%
       \rotatebox{90}{\footnotesize\url{www.xkcd.com}}}}
 
diff --git a/programming/lecture/programming.tex b/programming/lecture/programming.tex
index 80eb762..e05e381 100644
--- a/programming/lecture/programming.tex
+++ b/programming/lecture/programming.tex
@@ -190,8 +190,8 @@ represented (table~\ref{dtypestab}).
     Data type & memory demand & range & example \erh \\ \hline
     \code{single} & 32 bit & $\approx -3.4^{38}$ to $\approx 3.4^{38}$ & Floating point numbers.\erb \\ 
     \code{double} & 64 bit & $\approx -10^{308}$ to $\approx 10^{308}$ &
-    Floating point numbers.\erb\\ \code{int} & 64 bit & $-2^{31}$
-    to $2^{31}-1$ & Integer values. \\ \code{int16} & 16 bit &
+    Floating point numbers.\erb\\ \code{int} & 64 bit & $-2^{63}$
+    to $2^{63}-1$ & Integer values. \\ \code{int16} & 16 bit &
     $-2^{15}$ to $2^{15}-1$ & Digitizes measurements. \\ \code{uint8}
     & 8 bit & $0$ bis $255$ & Digitized intensities of colors in
     images. \\ \hline
@@ -402,6 +402,17 @@ ans =
   could you find out the size of the \varcode{a} in the 2nd dimension?
 \end{exercise}
 
+\begin{important}[The : (colon) operator]
+  The colon \code[Operator!colon@:]{:} operator is often used when working with vectors. It has multiple purposes.
+  \begin{enumerate}
+    \item In the simplest form,  \code{x = a:b} with \code{a} and \code{b} being two numbers, it creates 
+  a vector \code{x} containing the numbers \code{a} to \code{b} in integer steps. In \matlab{} the borders $a$ and $b$ are included $[a, b]$ or $a\leq x \leq b$.
+    \item In the form \code{x = a:c:b} the vector \code{x} uses a \emph{stepsize} of \code{c} to create the range of numbers.
+    \item When used in the context of indexing such as \code{x(:)} all elements of the vector x are accessed.
+    \item As vectors are often used for indexing in other vectors one use the colon operator to create such vectors implicitely, e.g. \varcode{x(1:2:end)} to access every seond element of \code{x}. 
+  \end{enumerate}  
+\end{important}
+
 \subsubsection{Operations on vectors}
 
 Similarly to the scalar variables discussed above we can work with