I'm reading 3.5.2 of PRML book and am confused about the result of taking derivative of marginal likelihood function with regard to alpha. In particular regarding this function:

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And according to the book the derivative with regard to alpha is:

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So it seems m_N is not a function of alpha at all. But clearly it is a function of alpha according to this formula:

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I must have missed something very obvious.


  • $\begingroup$ See this answer. st 30 characters; you entered 16. $\endgroup$ – Don Slowik Oct 3 '19 at 22:31
  • 1
    $\begingroup$ Great answer there, thanks a lot! $\endgroup$ – Yong Zou Apr 23 at 4:43

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