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\begin{eqnarray}\label{eq4}
IP_i=X\cdot y_i&=&(x_{n-1}x_{n-2}\cdots x_1 x_0)\cdot y_i\\
&=& x_{n-1}y_i,x_{n-2}y_i,\cdots x_1b_i,x_0y_i\nonumber \\
&=& p_{n-1,i},p_{n-2,i},\cdots p_{1,i},p_{0,i}\nonumber 
\end{eqnarray}

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