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tikenn · #1 07-12-2017, 06:41 PM

I think this is similar to the answer provided for problem 3.5, but I am having a difficult time understanding why, in Problem 3.4, the error is continuous and differentiable at the point $y_n\textbf{w}^T\textbf{x}_n=1$ . I have the three cases looking like this so far:

$y_n\textbf{w}^T\textbf{x}_n>1$ in which I believe $E(\mathbf{x}_n) = 0$
$y_n\textbf{w}^T\textbf{x}_n<1$ in which I believe $E(\mathbf{x}_n) = (1 - y_n\textbf{w}^T\textbf{x}_n)^2$
$y_n\textbf{w}^T\textbf{x}_n=1$ in which I believe $E(\mathbf{x}_n) = 0$

These cases would make $y_n\textbf{w}^T\textbf{x}_n=1$ non-differentiable because the derivatives from the left and right are different. Am I evaluating the error from the book wrong --> $e_n(\textbf{w})=(\max(0,1-y_n\textbf{w}^T\textbf{x}_n))^2$ ?