1 files changed, 96 insertions, 0 deletions
diff --git a/vorlesungen/slides/2/hilbertraum/rieszbeispiel.tex b/vorlesungen/slides/2/hilbertraum/rieszbeispiel.tex
new file mode 100644
index 0000000..e2c26f5
--- /dev/null
+++ b/vorlesungen/slides/2/hilbertraum/rieszbeispiel.tex
@@ -0,0 +1,96 @@
+%
+% rieszbeispiel.tex -- slide template
+%
+% (c) 2021 Prof Dr Andreas Müller, OST Ostschweizer Fachhochschule
+%
+\bgroup
+\begin{frame}[t]
+\setlength{\abovedisplayskip}{5pt}
+\setlength{\belowdisplayskip}{5pt}
+\frametitle{Linearform auf $L^2$-Funktionen}
+\vspace{-20pt}
+\begin{columns}[t,onlytextwidth]
+\begin{column}{0.48\textwidth}
+\begin{block}{Linearform auf $\mathbb{C}^n$}
+\begin{align*}
+{\color{blue}x}&=\begin{pmatrix}x_1\\x_2\\\vdots\\x_n\end{pmatrix},
+&
+f({\color{blue}x})
+&= 
+\begin{pmatrix}f_1&f_2&\dots&f_n\end{pmatrix} {\color{blue}x}
+\\
+{\color{red}v}&=
+\rlap{$
+\begin{pmatrix}
+\overline{f}_1&\overline{f}_2&\dots&\overline{f}_n
+\end{pmatrix}^t
+\;\Rightarrow\;
+f({\color{blue}x})=\langle {\color{red}v},{\color{blue}x}\rangle
+$}
+\end{align*}
+\end{block}
+\end{column}
+\begin{column}{0.48\textwidth}
+\begin{block}{Linearform auf $L^2([a,b])$}
+\begin{align*}
+{\color{red}x}&\in L^2([a,b])
+\\
+f&\colon L^2([a,b]) \to \mathbb{C}
+: {\color{red}x} \mapsto f({\color{red}x})
+\intertext{Riesz-Darstellungssatz: $\exists {\color{blue}v}\in L^2([a,b])$}
+f({\color{red}x})
+&=
+\int_a^b {\color{blue}\overline{v}(t)}{\color{red}x(t)}\,dt
+\end{align*}
+\end{block}
+\end{column}
+\end{columns}
+\begin{center}
+\begin{tikzpicture}[>=latex,thick]
+\begin{scope}[xshift=-3.5cm]
+\def\s{0.058}
+\foreach \n in {0,...,5}{
+	\draw[color=red,line width=3pt]
+		({\n+\s},{1/(\n+0.5)}) -- ({\n+\s},0);
+	\node[color=red] at ({\n},{-0.2+1/(\n+0.5)})
+		[above right] {$v_\n\mathstrut$};
+	\draw[color=blue,line width=3pt]
+		({\n-\s},{0.4+0.55*sin(200*\n)+0.25*\n}) -- ({\n-\s},0);
+	\node[color=blue] at ({\n},{-0.2+0.4+0.55*sin(200*\n)+0.25*\n})
+		[above left] {$x_\n\mathstrut$};
+}
+\draw[->] (-0.6,0) -- (6,0) coordinate[label={$n$}];
+\draw[->] (-0.5,-0.1) -- (-0.5,2.5) coordinate[label={right:$x$}];
+\foreach \n in {0,...,5}{
+	\fill (\n,0) circle[radius=0.08];
+	\node at (\n,0) [below] {$\n$\strut};
+}
+\node at (5.6,0) [below] {$\cdots$\strut};
+\end{scope}
+\begin{scope}[xshift=3.5cm]
+\fill[color=red!40,opacity=0.5] 
+	plot[domain=0:5,samples=100] (\x,{1/(\x+0.5)})
+	--
+	(5,0) -- (0,0) -- cycle;
+\fill[color=blue!40,opacity=0.5]
+	plot[domain=0:5,samples=100] (\x,{0.4+0.55*sin(200*\x)+0.25*\x})
+	-- (5,0) -- (0,0) -- cycle;
+\draw[color=red,line width=1.4pt]
+	plot[domain=0:5,samples=100] (\x,{1/(\x+0.5)});
+\node[color=red] at (0,2) [right] {$x(t)$};
+
+\draw[color=blue,line width=1.4pt]
+	plot[domain=0:5,samples=100] (\x,{0.4+0.55*sin(200*\x)+0.25*\x});
+\node[color=blue] at (4.5,2) [right]{$v(t)$};
+
+\draw[->] (-0.6,0) -- (6.0,0) coordinate[label={$t$}];
+\draw[->] (-0.5,-0.1) -- (-0.5,2.5) coordinate[label={right:$x$}];
+\draw (0.0,-0.1) -- (0.0,0.1);
+\node at (0.0,0) [below] {$a$\strut};
+\draw (5.0,-0.1) -- (5.0,0.1);
+\node at (5.0,0) [below] {$b$\strut};
+\end{scope}
+\end{tikzpicture}
+\end{center}
+\end{frame}
+\egroup