Cauchy was born in Paris on August 21st, 1789. His father was a lawyer who was proficient in classical literature and had close contacts with Lagrange and Laplace, the great French mathematicians at that time. Cauchy's mathematical talents in his boyhood were highly appreciated by these two mathematicians. And predicted that Cauchy would become a great success in the future. Lagrange suggested to his father that he should "give Cauchy a solid literary education as soon as possible" so that his hobby would not lead him astray. Therefore, his father strengthened his literary education for Cauchy and made him show great talent in poetry.
From 187 to 181, Cauchy studied in the Institute of Technology and worked as a traffic and road engineer. Due to poor health, He accepted the advice of Lagrange and Laplace, gave up engineers and devoted himself to the study of pure mathematics. Cauchy's greatest contribution in mathematics was to introduce the concept of limit in calculus, and established a logically clear analysis system based on limit. This is the essence of the development history of calculus and also a great contribution made by Cauchy to the development of human science.
In 1821, Cauchy put forward the method of defining limit. The limit process was described by inequality, and it was improved by Weierstrass, which became the Cauchy limit definition or definition now. At least in essence, all the textbooks of calculus today still follow the definitions of limit, continuity, derivative, convergence and other concepts of Cauchy and others. His explanation of calculus was widely adopted by later generations. Cauchy made the most systematic and pioneering work on definite integral. He defined definite integral as the "limit" of sum. Before the definite integral operation, he emphasized the necessity of establishing the existence of integral. He first proved the basic theorem of calculus strictly by using the mean value theorem. Through Cauchy's and later Weierstrass's hard work, the basic concept of mathematical analysis was strictly discussed, thus ending the ideological confusion of calculus in the past 2 years and promoting calculus from the concept of geometry, Free from the complete dependence of movement and intuitive understanding, and make calculus develop into the most basic and largest mathematical discipline in modern mathematics.
The rigorous work of mathematical analysis had a great impact from the beginning. Cauchy put forward the theory of series convergence at an academic conference. After the meeting, Laplace hurried home. According to Cauchy's rigorous discrimination method, Check whether the series used in his masterpiece Celestial Mechanics converge one by one.
Cauchy's research achievements in other fields are also very rich. The calculus theory of complex variable function was founded by him. He also made outstanding contributions in algebra, theoretical physics, optics and elasticity theory. Cauchy's mathematical achievements are not only brilliant, but also amazing. The complete works of Cauchy have 27 volumes. There are more than 8 treatises. He is a prolific mathematician second only to Euler in the history of mathematics. His glorious name is remembered in many textbooks today along with many theorems and criteria.
As a scholar, he has quick thinking and outstanding achievements. From Cauchy's vast treatises and achievements, It's not hard to imagine how hard he worked all his life. But Cauchy is a man with complex personality. He is a loyal royalist, an enthusiastic Catholic, and a lonely scholar. Especially as a prestigious scientific master, he often ignores the creation of young scholars. For example, because Cauchy "lost" the groundbreaking manuscripts of talented young mathematicians Abel and Galois, Group theory came out about half a century later.
On May 23rd, 1857, Cauchy died in Paris. His last famous saying, "People will die, but their achievements will last forever", has been knocking on the hearts of generations of students for a long time.