this is faster and lower in memory but we have found that there are a number of problems where these types of first-order methods don't work at all and you need to use the the second-order methods in order to optimization optimize them well thank you why is theta minus Phi in the Gaussian prior this is a few slides ago the answer to this question though is that the the interpretation as a Gaussian prior it basically says that the prior is on Phi and Phi is normally distributed with a mean of theta the variance of that prior depends on the