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Old 10-07-2013, 09:27 AM
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magdon magdon is offline
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Default Re: Exercise 3.4

\hat y-y is not H\epsilon, but that is close. Recall y=Xw+\epsilon

Originally Posted by aaoam View Post
I'm having a bit of difficulty with 3.4b. I take \hat(y) - y and multiply by (XX^T)^{-1}XX^T, which ends up reducing the expression to just H\epsilon. However, then I can't use 3.3c in simplifying 3.3c, which makes me think I did something wrong. Can somebody give me a pointer?

Also, it'd be great if there was instructions somewhere about how to post in math mode. Perhaps I just missed them?
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