|
@@ -13,19 +13,24 @@
|
|
|
|
|
|
\textbf{Lösung:}
|
|
|
|
|
|
-\[P =
|
|
|
-\begin{pmatrix}
|
|
|
- 0 & 1 & 0 \\
|
|
|
- 1 & 0 & 0 \\
|
|
|
- 0 & 0 & 1
|
|
|
-\end{pmatrix}\]
|
|
|
-
|
|
|
-durch scharfes hinsehen.
|
|
|
-
|
|
|
-Nun $L, R$ berechnen:
|
|
|
-
|
|
|
-\begin{align}
|
|
|
- &\begin{gmatrix}[p]
|
|
|
+\begin{align*}
|
|
|
+ &
|
|
|
+ &
|
|
|
+ A^{(0)} &= \begin{gmatrix}[p]
|
|
|
+ 3 & 15 & 13 \\
|
|
|
+ 6 & 6 & 6 \\
|
|
|
+ 2 & 8 & 19
|
|
|
+ \rowops
|
|
|
+ \swap{0}{1}
|
|
|
+ \end{gmatrix}
|
|
|
+ &\\
|
|
|
+ P^{(1)} &= \begin{pmatrix}
|
|
|
+ 0 & 1 & 0\\
|
|
|
+ 1 & 0 & 0\\
|
|
|
+ 0 & 0 & 1
|
|
|
+ \end{pmatrix},
|
|
|
+ &
|
|
|
+ A^{(1)} &= \begin{gmatrix}[p]
|
|
|
6 & 6 & 6 \\
|
|
|
3 & 15 & 13 \\
|
|
|
2 & 8 & 19
|
|
@@ -33,128 +38,48 @@ Nun $L, R$ berechnen:
|
|
|
\add[\cdot (-\frac{1}{2})]{0}{1}
|
|
|
\add[\cdot (-\frac{1}{3})]{0}{2}
|
|
|
\end{gmatrix}
|
|
|
- \\
|
|
|
- = \begin{pmatrix}
|
|
|
- 1 & 0 & 0 \\
|
|
|
- -\frac{1}{2} & 1 & 0 \\
|
|
|
- -\frac{1}{3} & 0 & 1
|
|
|
- \end{pmatrix} \cdot
|
|
|
- &\begin{gmatrix}[p]
|
|
|
+ &\\
|
|
|
+ L^{(2)} &= \begin{pmatrix}
|
|
|
+ 1 & 0 & 0\\
|
|
|
+ -\frac{1}{2} & 1 & 0\\
|
|
|
+ -\frac{1}{3} & 0 & 1
|
|
|
+ \end{pmatrix},
|
|
|
+ &
|
|
|
+ A^{(2)} &= \begin{gmatrix}[p]
|
|
|
6 & 6 & 6 \\
|
|
|
0 & 12 & 10 \\
|
|
|
0 & 6 & 17
|
|
|
\rowops
|
|
|
\add[\cdot (-\frac{1}{2})]{1}{2}
|
|
|
\end{gmatrix}
|
|
|
- \\
|
|
|
- = \begin{pmatrix}
|
|
|
- 1 & 0 & 0 \\
|
|
|
- 0 & 1 & 0 \\
|
|
|
- 0 & -\frac{1}{2} & 1
|
|
|
- \end{pmatrix} \cdot
|
|
|
- \begin{pmatrix}
|
|
|
- 1 & 0 & 0 \\
|
|
|
- -\frac{1}{2} & 1 & 0 \\
|
|
|
- -\frac{1}{3} & 0 & 1
|
|
|
- \end{pmatrix} \cdot
|
|
|
- &\begin{gmatrix}[p]
|
|
|
+ &\\
|
|
|
+ L^{(3)} &= \begin{pmatrix}
|
|
|
+ 1 & 0 & 0\\
|
|
|
+ 0 & 1 & 0\\
|
|
|
+ 0 & -\frac{1}{2} & 1
|
|
|
+ \end{pmatrix},
|
|
|
+ &
|
|
|
+ A^{(3)} &= \begin{gmatrix}[p]
|
|
|
6 & 6 & 6 \\
|
|
|
0 & 12 & 10 \\
|
|
|
0 & 0 & 12
|
|
|
- \colops
|
|
|
- \add[\cdot (-1)]{0}{1}
|
|
|
- \add[\cdot (-1)]{0}{2}
|
|
|
\end{gmatrix}
|
|
|
- \\
|
|
|
- = \begin{pmatrix}
|
|
|
- 1 & 0 & 0 \\
|
|
|
- -\frac{1}{2} & 1 & 0 \\
|
|
|
- -\frac{1}{12} & - \frac{1}{2} & 1
|
|
|
- \end{pmatrix} \cdot
|
|
|
- &\begin{gmatrix}[p]
|
|
|
- 6 & 0 & 0 \\
|
|
|
- 0 & 12 & 10 \\
|
|
|
- 0 & 0 & 12
|
|
|
- \colops
|
|
|
- \add[\cdot (-\frac{10}{12})]{1}{2}
|
|
|
- \end{gmatrix}
|
|
|
- \cdot
|
|
|
- \begin{pmatrix}
|
|
|
- 1 & -1 & -1 \\
|
|
|
- 0 & 1 & 0 \\
|
|
|
- 0 & 0 & 1
|
|
|
- \end{pmatrix}
|
|
|
- \\
|
|
|
- = \begin{pmatrix}
|
|
|
- 1 & 0 & 0 \\
|
|
|
- -\frac{1}{2} & 1 & 0 \\
|
|
|
- -\frac{1}{12} & - \frac{1}{2} & 1
|
|
|
- \end{pmatrix} \cdot
|
|
|
- &\begin{gmatrix}[p]
|
|
|
- 6 & 0 & 0 \\
|
|
|
- 0 & 12 & 0 \\
|
|
|
- 0 & 0 & 12
|
|
|
- \colops
|
|
|
- \mult{0}{\cdot \frac{1}{6}}
|
|
|
- \mult{1}{\cdot \frac{1}{12}}
|
|
|
- \mult{2}{\cdot \frac{1}{12}}
|
|
|
- \end{gmatrix}
|
|
|
- \cdot
|
|
|
- \begin{pmatrix}
|
|
|
- 1 & -1 & -1 \\
|
|
|
- 0 & 1 & 0 \\
|
|
|
- 0 & 0 & 1
|
|
|
- \end{pmatrix}
|
|
|
- \cdot
|
|
|
- \begin{pmatrix}
|
|
|
- 1 & 0 & 0 \\
|
|
|
- 0 & 1 & -\frac{10}{12} \\
|
|
|
- 0 & 0 & 1
|
|
|
- \end{pmatrix}
|
|
|
- \\
|
|
|
- = \begin{pmatrix}
|
|
|
- 1 & 0 & 0 \\
|
|
|
- -\frac{1}{2} & 1 & 0 \\
|
|
|
- -\frac{1}{12} & - \frac{1}{2} & 1
|
|
|
- \end{pmatrix} \cdot
|
|
|
- &\begin{gmatrix}[p]
|
|
|
- 1 & 0 & 0 \\
|
|
|
- 0 & 1 & 0 \\
|
|
|
- 0 & 0 & 1
|
|
|
- \end{gmatrix}
|
|
|
- \cdot
|
|
|
- \begin{pmatrix}
|
|
|
- 1 & -1 & -\frac{1}{6} \\
|
|
|
- 0 & 1 & -\frac{5}{6} \\
|
|
|
- 0 & 0 & 1
|
|
|
- \end{pmatrix}
|
|
|
- \cdot
|
|
|
- \begin{pmatrix}
|
|
|
- \frac{1}{6} & 0 & 0 \\
|
|
|
- 0 & \frac{1}{12} & 0 \\
|
|
|
- 0 & 0 & \frac{1}{12}
|
|
|
+\end{align*}
|
|
|
+
|
|
|
+Es gilt:
|
|
|
+
|
|
|
+\begin{align}
|
|
|
+ L^{(3)} \cdot L^{(2)} \cdot \underbrace{P^{(1)}}_{=: P} \cdot A^{0} &= \underbrace{A^{(3)}}_{=: R}\\
|
|
|
+ \Leftrightarrow P A &= (L^{(3)} \cdot L^{(2)})^{-1} \cdot R \\
|
|
|
+ \Rightarrow L &= (L^{(3)} \cdot L^{(2)})^{-1}\\
|
|
|
+ &= \begin{pmatrix}
|
|
|
+ 1 & 0 & 0\\
|
|
|
+ \frac{1}{2} & 1 & 0\\
|
|
|
+ \frac{1}{3} & \frac{1}{2} & 1
|
|
|
\end{pmatrix}
|
|
|
- \\
|
|
|
- = \underbrace{\begin{pmatrix}
|
|
|
- 1 & 0 & 0 \\
|
|
|
- -\frac{1}{2} & 1 & 0 \\
|
|
|
- -\frac{1}{12} & - \frac{1}{2} & 1
|
|
|
- \end{pmatrix}}_L \cdot
|
|
|
- &\begin{gmatrix}[p]
|
|
|
- 1 & 0 & 0 \\
|
|
|
- 0 & 1 & 0 \\
|
|
|
- 0 & 0 & 1
|
|
|
- \end{gmatrix}
|
|
|
- \cdot \underbrace{\frac{1}{72}
|
|
|
- \begin{pmatrix}
|
|
|
- 12 & -6 & -1 \\
|
|
|
- 0 & 6 & -5 \\
|
|
|
- 0 & 0 & 6
|
|
|
- \end{pmatrix}}_R
|
|
|
\end{align}
|
|
|
|
|
|
-ACHTUNG: Ich habe mich irgendwo verrechnet!
|
|
|
-Siehe \href{http://www.wolframalpha.com/input/?i=%7B%7B1%2C0%2C0%7D%2C%7B-1%2F2%2C1%2C0%7D%2C%7B-1%2F12%2C-1%2F2%2C1%7D%7D*%7B%7B12%2C-6%2C-1%7D%2C%7B0%2C6%2C-5%7D%2C%7B0%2C0%2C6%7D%7D}{WolframAlpha}
|
|
|
+Nun gilt: $P A = L R = A^{(1)}$ (Kontrolle mit \href{http://www.wolframalpha.com/input/?i=%7B%7B1%2C0%2C0%7D%2C%7B0.5%2C1%2C0%7D%2C%7B1%2F3%2C0.5%2C1%7D%7D*%7B%7B6%2C6%2C6%7D%2C%7B0%2C12%2C10%7D%2C%7B0%2C0%2C12%7D%7D}{Wolfram|Alpha})
|
|
|
|
|
|
\subsection*{Teilaufgabe b}
|
|
|
|
|
@@ -182,7 +107,7 @@ Falls $A$ symmetrisch ist, gilt:
|
|
|
& \Leftrightarrow \text{es gibt eine Cholesky-Zerlegung $A=GG^T$ mit $G$ ist reguläre untere Dreiecksmatrix}\\
|
|
|
\end{align*}
|
|
|
|
|
|
-Mit dem Hauptminor-Kriterium gilt:
|
|
|
+\subsubsection*{Lösung 1: Hauptminor-Kriterium}
|
|
|
|
|
|
\begin{align}
|
|
|
\det(A_1) &= 9 > 0\\
|
|
@@ -193,3 +118,15 @@ Mit dem Hauptminor-Kriterium gilt:
|
|
|
\end{vmatrix} = 9 - 16 < 0\\
|
|
|
&\Rightarrow \text{$A$ ist nicht positiv definit}
|
|
|
\end{align}
|
|
|
+
|
|
|
+\subsubsection*{Lösung 2: Cholesky-Zerlegung}
|
|
|
+\begin{align}
|
|
|
+ l_{11} &= \sqrt{a_{11}} = 3\\
|
|
|
+ l_{21} &= \frac{a_{21}}{l_{11}} = \frac{4}{3}\\
|
|
|
+ l_{31} &= \frac{a_{31}}{l_{11}} = 4\\
|
|
|
+ l_{22} &= \sqrt{a_{21} - {l_{21}}^2} = \frac{2 \sqrt{5}}{3}\\
|
|
|
+ \dots
|
|
|
+\end{align}
|
|
|
+
|
|
|
+ACHTUNG: Noch nicht fertig! Irgendwo muss was negatives unter einer
|
|
|
+Wurzel kommen!
|