#1




HW5 Q8~9: Is the line a straight line?
In homework 5, questions 8 and 9, is the random line to be chosen as a target function f(x) a straight line?
I feel it's a rather silly question ... but I am somewhat confused on what target function to pick. 
#2




Re: HW5 Q8~9: Is the line a straight line?
Yes, it is a straight line.

#3




Re: HW5 Q8~9: Is the line a straight line?
.. Unless someone left the line out in the rain; then it may warp, and no longer be straight.

#4




Re: HW5 Q8~9: Is the line a straight line?
Am I missing something or is the name f(x) a bit misleading? In the slides for logistic regression f(x) is explicitly referred to as a probability. However in the exercise it is a linear function that may also take negative function values.
It seems the function f(x) corresponds to the line that is learned inside the sigmoid function, but that's not the final g(x) we are learning (which should approximate f(x) ) ? 
#5




Re: HW5 Q8~9: Is the line a straight line?
Quote:
In this problem, though, stochastic gradient descent is the focus. The fact that probabilities are involved is only really interesting because of the error function: if the data are linearly separable (as they are here), but E_in is not zero, then it has behaved differently from PLA, even if its goal is the same here. 
#6




Re: HW5 Q8~9: Is the line a straight line?
Thank you for clarifying. Meanwhile I realized that the excercise just utilizes a straight line to define f(x), but f(x) itself is not the straight line...
In hindsight things are (almost) always obvious 
Tags 
hw5, logistic regression 
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