2020 Homework 5 Forward Energy Error

[bwcurless]

I've been doing these exercises on my own but couldn't get the test code with the 3x3 matrix in the forward energy part of the problem set to pass. Upon closer inspection, it looks like the forward energy may be computed with the difference in energy, not the difference in image intensity as the lecture notes say it should be. Am I wrong in my understanding of how this is supposed to work? For instance I expect the solution cost for the middle value of the 3x3 test matrix to be the minimum of 2.5+0.5=3, 0.5+0.5+0.5=1.5, 3+0.5+1=4.5 for vertical, left and right seams, which is 1.5 yet the solution cost claims it to be 2. The only way I can get 2 for this cost is if I compute the new introduced energy as the difference in energy, not the difference in pixel intensity. I can make a PR for it if I'm not mistaken here, although I also don't really know what the boundary conditions are supposed to be in this case.