I am an engineer. I majored in mechanical in my college days. However, even if I have left school and been working for many years, I still find math attractive to me. With self-study and online resources like OCW, I have been trying to review the courses which I did not pay sufficient effort, like Calculus and Engineering Mathematics, and explore the interesting field which I did not have a chance to reach such as Analysis. I am glad I can start to learn more about math for no pragmatic reasons, not for credit courses, not for my current job, but only for fun.