非常的清晰！

Thank you, many of your pictures have helped me understand a lot, this work is very meaningful!

oh so the log trick is like this: gradient of log f(x) = f'(x)/f(x) . This mean that f'(x) = f(x) log f(x). So that will allow us to replace f(x) log f(x) as f'(x) and go forward.

What does the log-trick used in step 3 mean?