#1




Hw4 q4
What is the range of a? [1,1] of [INF, +INF] ?

#2




Re: Hw4 q4
From my testing, a is within +/ pi.
This follows from the max/min gradient of sin(pi.x) = pi . cos(pi . x) It is ok to use a larger range, just that the program will run slower. 
#3




Re: Hw4 q4
Thanks, but now I think I've hit another snag. Is the bias in class surely 0.21? My calculation shows it as exactly 0.31...

#4




Re: Hw4 q4
I can't help with that but I have a more basic question. To get ax on two points, do we take the "a" based on the average of the two points
(y1+y2)/(x1+x2) or calculate "a" on each point and take the average? 1/2 (y1/x1 + y2/x2) 
#5




Re: Hw4 q4
The two give very different results, but shouldn't they be equivalent in grading?

#6




Re: Hw4 q4
Quote:
__________________
Where everyone thinks alike, no one thinks very much 
#7




Re: Hw4 q4
I don't think (y1+y2)/(x1+x2) is valid, i.e., not the best choice for the line a*x. Maybe 1/2*(y1/x1 + y2/x2) is close but is it correct?
Seems like the way to go is to get a formula for the distance function (squared distance) and then minimize it. The answer from that process differs from 1/2*(y1/x1 + y2/x2). EDIT: Prof. Mostafa posted while I was checking that result. 
#8




Re: Hw4 q4
Quote:

#9




Re: Hw4 q4
In Lecture 8 slide 15, for y=ax+b, g_bar passes through the origin even though it is not forced to. This is reasonable due to the 'symmetry' of the curve.

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