Since17th century, the concepts and skills of calculus have been continuously expanded and widely used to solve various practical problems in astronomy and physics, and great achievements have been made. But until19th century, in the development of calculus, the rigor of its mathematical analysis has not been solved. In the eighteenth century, many great mathematicians, including Newton and Leibniz, realized this problem and tried to solve it, but they failed to solve it successfully. Throughout the18th century, the foundation of calculus was confusing, and many British mathematicians were likely to doubt all the work of calculus, because they were still bound by ancient Greek geometry. This problem was not completely solved by French mathematician Cauchy until the second half of the19th century. Cauchy's limit existence criterion injects rigor into calculus and is the basis of limit theory. The establishment of limit theory makes calculus based on strict analysis, which also laid the foundation for the development of mathematics in the 20th century.

Note: In the Middle Ages (14-17th century), European mathematics developed greatly, and China was basically at a standstill (Ming and Qing Dynasties). So mathematicians in our country have nothing to do with calculus.