nn_1.tex

%
% CC BY-SA 4.0  / 2019-06-29 Jean-Luc Charles / Jean-luc.charles@ensam.eu
%
\documentclass[border=0.125cm]{standalone}
\usepackage{tikz}
\usetikzlibrary{positioning,decorations.pathreplacing,arrows}
\begin{document}

\tikzset{%
  neuron/.style={
    circle,
    draw,
    minimum size=1cm
  },
  squa/.style={
    draw,
    inner sep=2pt,
    font=\Large,
    join = by -latex
  },
}

\begin{tikzpicture}[x=1.5cm, y=1.5cm, >=stealth]

  \node [label=above:\parbox{2cm}{\centering Input\\stimuli}] at (0, 1.5) (x1)  {$x_1$};
  \node [] at (0, 0.5) (x2) {$x_2$};
  \node [] at (0, -0) (vdots) {$\vdots$};
  \node [] at (0, -0.7) (xn) {$x_n$};
  \node [label=above:\parbox{2cm}{\centering Bias}] at (2, 1.8) (bias) {$-1$};
  \node [squa, label=above:{\parbox{2cm}{\centering Activation\\function}}] at (4.4, 0.15) (F) {$f$};
  \node [label=above:\parbox{2cm}{\centering Output}] at (6, 0.15) (y) {$y = f(\sum_i{w_{i}\,x_i} - b)$};
  
  \node [neuron/.try] (output) at (2,0.15) {\Huge{$\displaystyle\Sigma$}};
  
  \draw [o-latex] (x1) -- (output);
  \draw [o-latex] (x2) -- (output);
  \draw [o-latex] (xn) -- (output);
  \draw [o-latex] (bias) -- (output);
  \draw [->] (output) -- (F);
  \draw [->] (F) -- (y);

  \node [] at (2.2,1) () {$b$} ;
  \node [] at (1,1) () {$w_1$} ;
  \node [] at (1,.5) () {$w_2$} ;
  \node [] at (1, -0.45) () {$w_n$} ;
  \node [] at (3.2, 0.3) () {$\sum_i{w_{i}\,x_i} - b$};


\end{tikzpicture}

\end{document}