Newtons method
Simple, numerical computing.
Sometimes, I get these ideas, and I just have to sit down, write it down and get it out of my head. If it's a good idea, I prefer to do it in such a way as to have some use of it, and sometimes I do it just to see if it will work. I'm talking about ideas for computer programs, of course, and when I say write it down, I mean writing it down in a programming language and then possibly run the program. I've had one of these days today.