I don't believe there is a specific Mathematical definition for "intractable." An "intractable" problem is simply one that cannot be solved. In this case, the integral can't be expressed in terms of a finite number of closed form functions (like polynomials, trig functions, logs, etc.).Originally Posted byabiy3000

I usually reserve the use of the word "intractable" to describe problems that look easy, but are in fact impossible. This is definately an integral I would call "intractable!"

-Dan