Guys I read Shaum's outline of differential equations. I understand that for different type of differential equation you need different method to solve the equation. My problem is i am curious how these methods to solve differential equations came about. I want to get a good understanding of differential equations, as probably in the future i hope to derive my own formula to solve non linear water wave ;9 Any good book to recommend me to read? Nothing too rigourous, I am only a engineer with light mathematical training. Thanks.