答案1
以下是解决方案的草图
\documentclass{article}
\usepackage{amsmath}
\usepackage{tikz}
\usetikzlibrary{positioning,calc}
\begin{document}
\begin{tikzpicture}
\node[draw,minimum height=2em, minimum width=8em](pred) {(1) Prediction};
\node[below=0em of pred](equa1) {
$\left\{\begin{aligned}
A_t&= F A_{t-1}\\
P_t&=F P_{t-1}
\end{aligned}\right.
$};
\node[below left=9em and 5em, draw,minimum height=2em, minimum width=8em](update){(2) Update(filter)};
\node[below=0em of update](equa2) {
$\left\{\begin{aligned}
A_t&= F A_{t-1}\\
P_t&=F P_{t-1}\\
K_t&=K_{t-1}\\
\end{aligned}\right.
$};
\node[below right=9em and 5em, draw,minimum height=2em, minimum width=8em](done){(2) (2) Do nothing};
\draw[->](equa1.south) |- ++(-1em, -1em) -- node[left]{data is existing}(update);
\draw[->](equa1.south) |- ++(1em, -1em) -- node[right]{data is missing}(done);
\draw[->] (done.east) --++(2em,0) |- (pred);
\draw[->] (equa2.west) --++(-2em,0) |- (pred);
\node[below=15em of pred,draw,minimum height=2em, minimum width=8em] (filter){(3) Filter};
\draw[->] ($(pred)+(0,-8em)$) -- (filter);
\end{tikzpicture}
\end{document}