32 lines
1.3 KiB
TeX
32 lines
1.3 KiB
TeX
\chapter{Lineare Algebra}
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\section{Allgemeines}
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\subsection*{Definitionen}
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\subsubsection*{Levi-Civita-Symbol:}
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\begin{math}
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\varepsilon_{12\dots n} = 1 \\
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\varepsilon_{ij\dots u\dots v\dots} = -\varepsilon_{ij\dots v\dots u\dots}\\
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\varepsilon_{ij\dots u\dots u\dots} = 0 \\
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\levicivita{i,j,k} =
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\begin{cases}
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+1, & \mbox{falls }(i,j,k,\dots) \mbox{ eine gerade Permutation von } (1,2,3,\dots) \mbox{ ist,} \\
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-1, & \mbox{falls }(i,j,k,\dots) \mbox{ eine ungerade Permutation von } (1,2,3,\dots) \mbox{ ist,} \\
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0, & \mbox{wenn mindestens zwei Indizes gleich sind.}
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\end{cases}
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(\vec{a} \times \vec{b})_i = \sum_{j=1}^3 \sum_{k=1}^3 \levicivita{ijk} a_j b_k \\
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\vec{a} \times \vec{b} = \levicivita{ijk} a_j b_k \vec{e_i} = \levicivita{ijk} a_i b_j \vec{e_k} \\
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\det A = \levicivita{i_1 i_2 \dots i_n} A_{1i_1} A_{2i_2} \dots A_{ni_n}
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\end{math}
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\subsubsection*{Kronecker-Delta}
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$\krondelta{i,j}= \begin{cases} 1 & \mbox{falls } i=j \\ 0 & \mbox{falls } i \neq j \end{cases}$ \\s
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Die $n\times n$-Einheitsmatrix kann als $(\krondelta{ij})_{i,j\in\{1,\ldots,n\}}$ geschrieben werden.
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\section{Matrix-Operationen}
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\subsection*{Inversion}
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\begin{math}
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\hypertarget{fs_mtrx_inv_2d}{A^{-1} = \inlinematrix{a & b \\ c & d}^{-1} = \frac{1}{ad - bc} \inlinematrix{d & -b \\ -c & a}}
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\end{math}
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