According to the epsilon-delta definition, a function f of two real variables is said to be continuous at (x0,y0) if for any ε > 0 there exists a δ such that | f (x,y) – f (x0,y0)| < ε whenever |(x,y) – (x0,y0)| < δ.
Demos
Continuity
Exercises
Try using the demo to test the continuity of the following functions at several points, particularly those that you suspect to be points of discontinuity.