Does anyone know of a formal definition for a "closed form" solution?
For example, I would say 1/(1-x) is a closed form for the geometric series it generates.
But what about exp(x) or sin(x)? Are they closed forms? If so, because they are represented by converging series? If so, then what about bessel function J(x), or for that matter, any converging sereis solution?
The more I think about it the less certain I am I know what it is, I dont even know one if I see one anymore!