Forward–backward algorithm: Difference between revisions

Content deleted Content added
Major mistake corrected for the backward message formula. But someone should recompute the final results in the example, as I don't have time to do it.
Line 83:
 
Now that we have defined the forward probabilities, we continue to compute the backward probabilities. Again the matrices appear in the order as in the backward formula above.
 
'''=> Someone should recompute the final results because the formula for the backward message was previously wrong and was corrected above and in the following equations, but not the finalresult was not matrixrecomputed.'''
 
<math>
\mathbf{b_{5:5}} = \begin{pmatrix} 0.7 & 0.3 \\ 0.3 & 0.7 \end{pmatrix}\begin{pmatrix}0.9 & 0.0 \\ 0.0 & 0.2 \end{pmatrix}\begin{pmatrix}1.0000 & 1.0000 \end{pmatrix}=\begin{pmatrix}0.5984 & 0.0543\end{pmatrix}=\begin{pmatrix}0.9168 & 0.0831 \end{pmatrix}
</math>
 
<math>
\mathbf{b_{4:5}} = \begin{pmatrix} 0.7 & 0.3 \\ 0.3 & 0.7 \end{pmatrix}\begin{pmatrix}0.9 & 0.0 \\ 0.0 & 0.2 \end{pmatrix}\begin{pmatrix}0.9168 & 0.0831 \end{pmatrix}=\begin{pmatrix}0.7308 & 0.2691\end{pmatrix}=\begin{pmatrix}0.8593 & 0.1407 \end{pmatrix}
</math>
 
<math>
\mathbf{b_{3:5}} = \begin{pmatrix} 0.7 & 0.3 \\ 0.3 & 0.7 \end{pmatrix}\begin{pmatrix}0.1 & 0.0 \\ 0.0 & 0.8 \end{pmatrix}\begin{pmatrix}0.8593 & 0.1407 \end{pmatrix}=\begin{pmatrix}0.0178 & 0.0845\end{pmatrix}=\begin{pmatrix}0.1739 & 0.8260 \end{pmatrix}
</math>
 
<math>
\mathbf{b_{2:5}} = \begin{pmatrix} 0.7 & 0.3 \\ 0.3 & 0.7 \end{pmatrix}\begin{pmatrix}0.9 & 0.0 \\ 0.0 & 0.2 \end{pmatrix}\begin{pmatrix}0.1739 & 0.8260 \end{pmatrix}=\begin{pmatrix}0.1405 & 0.0189\end{pmatrix}=\begin{pmatrix}0.8814 & 0.1185 \end{pmatrix}
</math>
 
<math>
\mathbf{b_{1:5}} = \begin{pmatrix} 0.7 & 0.3 \\ 0.3 & 0.7 \end{pmatrix}\begin{pmatrix}0.9 & 0.0 \\ 0.0 & 0.2 \end{pmatrix}\begin{pmatrix}0.8814 & 0.1185 \end{pmatrix}=\begin{pmatrix}0.4600 & 0.0462\end{pmatrix}=\begin{pmatrix}0.9087 & 0.0912 \end{pmatrix}