# how to get dual of this optimization problem?

How to solve optimization problem:

Given pairs $(x_i, y_i), x_i \in R^n , y_i \in R$ minimize (logistic regression):$\min \frac{1}{2} ||w||^2 + \sum_i^{i=m}\log(1+\exp(-y w\cdot x_i))$. How to do that? I know the dual form is: $\min_{\alpha} D(\alpha)= \frac{1}{2}\sum_{i, j}\alpha_i \alpha_j y_i y_j x_i \cdot x_j + \sum_i\alpha_i \log(\alpha_i) + (C-\alpha_i)\log(C-\alpha_i)$, subject to: $0\le \alpha_i\le C$. How to get dual?

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