Re: Q7  understanding coordinate descent
I am struggling to understand what I did wrong on this question.
The instructions are clear, I followed the method above (I think?), my answers to related questions (5 and 6) were correct, but my answer to question 7 is far far less than the correct answer. I got the answer level of accuracy in only 5 iterations (instead of 15), so I must have a serious problem with my algorithm.
I am wondering if I understand the term "only to reduce error". I took this to mean that after each step I recalculate the error, and if the error increased I do not apply the update. This helped rapid convergence significantly.
Upon researching why I got this answer wrong, I ran across some conflicting references that suggest "coordinate descent" can be much more efficient algorithm than GD because of some tricks to reuse parts of the calculation. I'm not sure what to think.
