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[progamming] fixes to colon operator box

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Jan Grewe 2020-12-20 13:41:49 +01:00
parent beab805065
commit fe77070636
1 changed files with 5 additions and 4 deletions
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9
programming/lecture/programming.tex
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@ -362,8 +362,8 @@ number of elements irrespective of the type of vector.
Listings~\ref{vectorelementslisting} and~\ref{vectorrangelisting} show
how the index is used to access elements of a vector. One can access
individual values by providing a single index or use the
\code[Operator!Matrix!:]{:} notation to access multiple values with a
single command.
\code[Operator!Matrix!:]{:} operator to access multiple values with a
single command (see also the info box below \ref{important:colon_operator}).
\begin{lstlisting}[label=vectorelementslisting, caption={Access to individual elements of a vector.}]
>> a = (11:20)
@ -403,13 +403,14 @@ ans =
\end{exercise}
\begin{important}[The : (colon) operator]
\label{important: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 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 ranging from $a$ to $b$ in steps of $c$.
\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}.
\item Vectors are often used for indexing in other vectors. To do so the colon operator is used to create such vectors implicitely, e.g. \varcode{x(1:2:end)} to access every second element of \code{x}.
\end{enumerate}
\end{important}