This is Cauchy's famous mathematical saying, which shows the importance of coefficient. If you want to simulate reality, the fewer parameters in the mathematical formula, the better. Because as long as there are enough parameters, nothing can't be described. Mathematics is never equal to numbers. Mathematics includes graphics, calculation, logic, reasoning and so on.

Cauchy criterion: After n terms are greater than a certain number, the absolute value of any two terms will always be less than a number (this number is uncertain but always greater than zero), then this series is the basic series (convergent sequences).

Extended data

Bernoulli, a master of mathematics, once said, "Only mathematics can explore infinity, and infinity is one of God's attributes". Physics, chemistry and biology are all limited disciplines, and "infinity" can represent the limit that can never be measured. The concept of infinity makes philosophers crazy, makes theologians sigh and makes many people deeply afraid.

On the other hand, Cauchy uses infinity to define a more precise mathematical meaning. He regarded the differential of mathematics as "the change of infinite hours" and expressed the integral as "the sum of infinite infinitesimals". Cauchy redefined calculus with infinity, which is still the beginning of every calculus textbook.

182 1 year, Cauchy's reputation spread far and wide. Students from as far away as Berlin, Madrid and St. Petersburg came to his classroom to attend classes. He also published a very famous "eigenvalue" theory and wrote: "In the field of pure mathematics, it seems that there is no actual physical phenomenon to prove it, and there is nothing in nature to explain it, but it is a paradise that mathematicians can see from a distance.