$\Huge X_{t}=c+\sum {{i=1}}^{p}\varphi{i}X_{{t-i}}+\varepsilon_{t}$
$\varphi_i$ are the parameters of the model, and $\varepsilon_t$ is the noise.
$\Huge p(\mathbf{x})=\Pi^{n^2}{i=1}p(x_i|x_1,\ldots,x{i-1})$