fig-code-back-propagation-2.tex

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\begin{tcolorbox}
[bicolor,sidebyside,width=13cm,righthand width=4cm,size=title,frame engine=empty,
 colback=blue!10!white,colbacklower=black!5!white]
 {\scriptsize
\begin{tabbing}
\texttt{XTensor x, loss, gold, h[5], w[5], b[5];} \\
\texttt{...} \\

\texttt{} \\
\texttt{h[1] = Relu(MMul(x, w[1]) + b[1]);} \\
\texttt{h[2] = Relu(MMul(h[1], w[2]) + b[2]);} \\
\texttt{h[3] = HardTanH(h[2]);} \\
\texttt{h[4] = Softmax(MMul(h[3], w[3]));} \\
\texttt{loss = CrossEntropy(h[4], gold);} \\

\texttt{} \\
\texttt{XNet net;}\\
{\texttt{net.Backward(loss);} //一行代码实现自动微分}\\

\texttt{} \\
\texttt{for(unsigned i = 0; i < 5; i++)\{} \\
\texttt{} \ \ \ \ ... // 通过{\texttt{w[i].grad}}访问参数的梯度\\
\texttt{\}}

\end{tabbing}
}
\tcblower
\begin{center}
\begin{tikzpicture}


\node [anchor=south,draw,rounded corners,inner sep=2pt,minimum width=8em,minimum height=1.0em,fill=red!30!white,blur shadow={shadow xshift=1pt,shadow yshift=-1pt}] (h1) at (0,0) {\tiny{x (input)}};
\node [anchor=south,draw,rounded corners,inner sep=2pt,minimum width=8em,minimum height=1.0em,fill=green!30!white,blur shadow={shadow xshift=1pt,shadow yshift=-1pt}] (h2) at ([yshift=1.0em]h1.north) {\tiny{h1 = Relu(x * w1 + b1)}};
\node [anchor=south,draw,rounded corners,inner sep=2pt,minimum width=8em,minimum height=1.0em,fill=green!30!white,blur shadow={shadow xshift=1pt,shadow yshift=-1pt}] (h3) at ([yshift=1.0em]h2.north) {\tiny{h2 = Relu(h1 * w2 + b2)}};
\node [anchor=south,draw,rounded corners,inner sep=2pt,minimum width=8em,minimum height=1.0em,fill=green!30!white,blur shadow={shadow xshift=1pt,shadow yshift=-1pt}] (h4) at ([yshift=1.0em]h3.north) {\tiny{h3 = HardTanh(h2)}};

\draw [->,very thick] (h1.north) -- (h2.south);
\draw [->,very thick] (h2.north) -- (h3.south);
\draw [->,very thick] (h3.north) -- (h4.south);

\node [anchor=south,draw,rounded corners,inner sep=2pt,minimum width=8.0em,minimum height=1.0em,fill=red!30!white,blur shadow={shadow xshift=1pt,shadow yshift=-1pt}] (slayer) at ([yshift=1.0em]h4.north) {\tiny{h4 = Softmax(h3 * w4) (output)}};
\node [anchor=south] (losslabel) at (slayer.north) {\scriptsize{\textbf{Cross Entropy Loss}}};

\draw [->,very thick] (h4.north) -- (slayer.south);

\end{tikzpicture}
\end{center}
\end{tcolorbox}
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