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Old 06-10-2013, 04:01 AM
skwong skwong is offline
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Join Date: Apr 2013
Location: Hong Kong
Posts: 13
Default Failed to find the bias term for Q14

For Q15, I coded to find the K centers for the RBF. Then use pseudo-inverse to find the w_k. Then have difficulty to find the b. I think it should be calculated by picking any point, and substitute into the formula for x and y:

y - \sum_{k=1}^{K}w_k exp(-\gamma \|x - \mu_{k}\|^2)

But, when I try it for all 100 points, all calculated b are different. Am I mis-understand something ? Or simply my program bug ? I read through all posts in the forum but cannot figure out any hints.

Further, from "on the right track" post, I used the 4 points sample to test my code, I can find those centres and clusters and phi, but cannot match the weights.

Without proper b, I cannot carry on the simulation for the remaining quiz.
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