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Old 10-17-2013, 10:22 PM
blunderboy blunderboy is offline
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Question Minimizing Ein by differentiation wr.t w



Can somebody please explain me how we got X' (X' is X Transpose) outside the braces after differentiation. Shouldn't it be X instead of X'.

When I revisited the lecture, I recalled professor saying it is not actually square. It is just transpose multipled by itself. This concept is not clear to me..

Appreciate the help
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Old 10-18-2013, 12:34 AM
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yaser yaser is offline
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Default Re: Minimizing Ein by differentiation wr.t w

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Originally Posted by blunderboy View Post


Can somebody please explain me how we got X' (X' is X Transpose) outside the braces after differentiation. Shouldn't it be X instead of X'.

When I revisited the lecture, I recalled professor saying it is not actually square. It is just transpose multipled by itself. This concept is not clear to me..

Appreciate the help
This comes from matrix calculus. The quantity || {\rm X}{\bf w}-{\bf y}||^2 is in fact ({\rm X}{\bf w}-{\bf y})^{\rm T} ({\rm X}{\bf w}-{\bf y}).

The squared matrix I referred to was {\rm X^T X}.
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Old 10-18-2013, 05:45 AM
blunderboy blunderboy is offline
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Default Re: Minimizing Ein by differentiation wr.t w

Aah..Got it. Thank you professor. I really appreciate the quick help from you. Your presence in the forum really help us. Thanks a lot!!
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Old 10-18-2013, 11:46 AM
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yaser yaser is offline
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Default Re: Minimizing Ein by differentiation wr.t w

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Aah..Got it. Thank you professor. I really appreciate the quick help from you. Your presence in the forum really help us. Thanks a lot!!
You are most welcome.
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