math-sylvester-diagonal-matrix.tex

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\begin{document}
\begin{preview}
\begin{equation*}
S^T \cdot A \cdot S = 
\left(
\begin{array}{*{9}{c}}
\tikzmark{a}1 \\
& \ddots & \\
& & \tikzmark{b}1 \\
& & & \tikzmark{c}-1 \\
& & & & \ddots & \\
& & & & & \tikzmark{d}-1\\
& & & & & & \tikzmark{e}\phantom{-}0 \\
& & & & & & & \ddots & \\
& & & & & & & & \tikzmark{f}\phantom{-}0 \\
\end{array}
\right)
\end{equation*}

\begin{tikzpicture}[remember picture,overlay]
\DrawBrace{a}{b}{r_{+}(s)-mal}
\DrawBrace{c}{d}{r_{-}(s)-mal}
\DrawBrace{e}{f}{r_{0}(s)-mal}
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\end{document}