LaTeX Forum

\documentclass{scrartcl}

\usepackage[latin1]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{amsmath, amssymb, tabu}

\begin{document}
\begin{equation}
\underline{\hat{p}(t + 1)} = \underline{\hat{p}(t)} + \underline{K(t + 1)}\underline{u}(t + 1)\left[y(t + 1) - \underline{u^{T}(t + 1)}\underline{\hat{p}(t)}\right]  
\end{equation} 
\end{document} 

\underbrace{\hat{p}(t + 1)}_{\text{Schätzwert}}

\tikzbrace[Verschiebung]{Text}{Beschriftung}[Pfadoptionen][Nodeoptionen]

\begin{equation}
	f(x) = \tikzbrace[-1ex]{\sin(x^2)-\sin(x^2)}{$=0$}[thick][font=\normalsize] + bx
\end{equation}

\documentclass[ngerman]{scrartcl}

\usepackage[T1]{fontenc}
\usepackage[latin1]{inputenc}
\usepackage{babel}

% Klammern in Formeln
\usepackage{tikz}
\usetikzlibrary{decorations.pathreplacing,calc}
\usepackage{xparse}
\NewDocumentCommand{\tikzbrace}{O{-2.5ex} m m O{} O{}}{%
	\tikz[remember picture]\coordinate (left brace coord);%
	#2%
	\tikz[remember picture]\coordinate (right brace coord);%
	\begin{tikzpicture}[remember picture,overlay,
		transform canvas={yshift=#1}]
		\draw [decoration={amplitude=1ex,brace},decorate,#4] %
			(right brace coord) -- (left brace coord)
			node [midway,below=1ex,font=\scriptsize,#5] {#3};
	\end{tikzpicture}
}

\begin{document}
\begin{equation}
	f(x) = \tikzbrace[-1ex]{\sin(x^2)-\sin(x^2)}{$=0$}[thick][font=\normalsize] + bx
\end{equation}
\end{document}