1. Convergence types include convergence sequence, function convergence, global convergence and local convergence. Convergence means approaching infinity, including infinitesimal or infinity. This function always approaches a certain value, which is called function convergence, that is, the function value is always constrained by a certain value, that is, convergence.
2. Definition of function convergence at a certain point. For any real number C, there is a definition that this number is greater than 0. For any two numbers A and B, it is satisfied that A minus B is greater than 0 and less than C, and the function f(x) converges to point x0. For any real number b>0, c > exists; 0, for any x 1, x2 satisfies 02, the order of convergence sequence is a series, and a is a fixed real number, if for any given b >；; 0, with a positive integer n, so that for any n >；; N, with |an-A|0, with n, when n >; N, if |a(n)-A| satisfies the above definition, the sequence {a(n)} is said to converge and converge to a.