The establishment of mathematical model does not mean the solution of the problem, but it is the basis of the problem, because at least the problem is explained clearly, which ensures that everyone's understanding of the problem is consistent.

Computer algorithm is a method and process to solve problems. Usually, algorithms are based on mathematical models. For example, if the problem of "exact solution of ordinary differential equations" is described by algebraic model and geometric model respectively, different algorithms will be derived: algebraic dynamics algorithm and geometric algorithm. Although the algorithm ideas are completely different, they all lead to the end of "problem solving".