%%%------------------------------------------------------------------------------------------------------------
\begin{tikzpicture}
%% a two-layer neural network
\begin{scope}
{
\draw [->,thick] (-1.8,0) -- (1.8,0);
\draw [->,thick] (0,0) -- (0,2);
\node [anchor=south] (heng1) at (1.6,-0.35) {\scriptsize{$x$}};
\node [anchor=south] (zong1) at (-0.2,1.6) {\scriptsize{$y$}};
\draw [-] (-0.05,1) -- (0.05,1);
\node [anchor=east,inner sep=1pt] (label1) at (0,1) {\tiny{1}};
\node [anchor=south east,inner sep=1pt] (label2) at (0,0) {\tiny{0}};
\node [anchor=south east,inner sep=1pt] (labela) at (0.2,-0.5) {\footnotesize{(a)}};
}
{\node [anchor=north west,align=left] (wblabel) at (-2,2) {{\scriptsize{\ $w'_{11}=0.7$}}};}
{\draw [-,very thick,ublue,rounded corners=0.1em] (-1.5,0) -- (0.5,0) -- (0.5,0.7) -- (1.5,0.7);}
\end{scope}
%---------------------------------------------------------------------------------------------
\begin{scope}[xshift=1.8in]
{
\draw [->,thick] (-1.8,0) -- (1.8,0);
\draw [->,thick] (0,0) -- (0,2);
\node [anchor=south] (heng1) at (1.6,-0.35) {\scriptsize{$x$}};
\node [anchor=south] (zong1) at (-0.2,1.6) {\scriptsize{$y$}};
\draw [-] (-0.05,1) -- (0.05,1);
\node [anchor=east,inner sep=1pt] (label1) at (0,1) {\tiny{1}};
\node [anchor=south east,inner sep=1pt] (label2) at (0,0) {\tiny{0}};
\node [anchor=south east,inner sep=1pt] (labelb) at (0.2,-0.5) {\footnotesize{(b)}};
}
{\node [anchor=north west,align=left] (wblabel) at (-2,2) {{\scriptsize{\ $w_{12}=100$}}\\[-0ex] {\scriptsize{\ $b_2=-6$}}\\[-0ex] {\scriptsize{\ $w'_{21}=0.7$}}};}
{\draw [-,very thick,ublue,rounded corners=0.1em] (-1.5,0) -- (0.5,0) -- (0.5,0.7) -- (0.7,0.7) -- (0.7,1.4) -- (1.5,1.4);}
\end{scope}
%-----------------------------------------------------------------------------------------------

\begin{scope}[xshift=3.6in]
{
\draw [->,thick] (-1.8,0) -- (1.8,0);
\draw [->,thick] (0,0) -- (0,2);
\node [anchor=south] (heng1) at (1.6,-0.35) {\scriptsize{$x$}};
\node [anchor=south] (zong1) at (-0.2,1.6) {\scriptsize{$y$}};
\draw [-] (-0.05,1) -- (0.05,1);
\node [anchor=east,inner sep=1pt] (label1) at (0,1) {\tiny{1}};
\node [anchor=south east,inner sep=1pt] (label2) at (0,0) {\tiny{0}};
\node [anchor=south east,inner sep=1pt] (labelc) at (0.2,-0.5) {\footnotesize{(c)}};
}
{\node [anchor=north west,align=left] (wblabel) at (-2,2) {\scriptsize{\ $w_{12}=100$}\\[-0ex] \scriptsize{\ $b_2=-6$}\\[-0ex] {\scriptsize{\ $w'_{21}=-0.7$}}};}
{\draw [-,very thick,ublue,rounded corners=0.1em] (-1.5,0) -- (0.5,0) -- (0.5,0.7) -- (0.7,0.7) -- (0.7,0) -- (1.5,0);}
\end{scope}

\end{tikzpicture}
%%%------------------------------------------------------------------------------------------------------------