LaTeX-examples/tikz/hopfield-network/hopfield-network.tex

\documentclass[varwidth=true, border=2pt]{standalone}
\usepackage{tikz}

\tikzstyle{neuron}=[draw,circle,minimum size=20pt,inner sep=0pt, fill=white]
\tikzstyle{stateTransition}=[very thick]
\tikzstyle{learned}=[text=red]

\begin{document}
    \newcommand\n{5}
    \begin{tikzpicture}[scale=1.3]
        \begin{scope}[rotate=17]
        %the multiplication with floats is not possible. Thus I split the loop in two.
        \foreach \number in {1,...,\n}{
            \node[neuron] (N-\number) at ({\number*(360/\n)}:1.5cm) {$x_\number$};
        }

        \foreach \number in {1,...,\n}{
            \foreach \y in {1,...,\n}{
                \draw[stateTransition] (N-\number) -- (N-\y);
            }
        }
        \end{scope}
        \begin{scope}[rotate=-1]
        \draw[learned,stateTransition] (N-1) -- (N-2) node [midway,above=-0.15cm,sloped] {$w_{1,2}$};
        \draw[learned,stateTransition] (N-1) -- (N-5) node [midway,above=-0.15cm,sloped] {$w_{1,5}$};
        \end{scope}
    \end{tikzpicture}
\end{document}