\documentclass{article}
\usepackage{graphicx}
\usepackage{tikz}
\usepackage{xepersian}
\settextfont{Yas}
\setdigitfont{Yas}
\begin{document}
\begin{figure}[htbp]
\centering
\tikzstyle{input}=[circle,thick,minimum size=.5cm,draw=black!80,fill=white!20]


\begin{tikzpicture}[>=latex,text height=1.5ex,text depth=0.25ex]
  \matrix[row sep=.25cm,column sep=0.5cm]
  {
  \node(1)[input]{$1$}; &\\
  \node (2) [input] {$x_1$}; & \node (5) [input] {$2$};\\
  $\vdots$ & \\
  \node (4) [input] {$x_n$}; & \\ };   
  
     \path[->]
    (1) edge node[above right] {$\scriptstyle{f(x)}$} (5);
    \path[->]
    (2) edge (5);
\path[->]
    (4) edge (5);

 \end{tikzpicture}
\caption{شبکه آدالاین}
\end{figure}

\end{document}