(leonhard euler Advertising 1707- 1783)

Euler was born in the Swiss city of Basel in 1707. At the age of 13, he went to university of basel to study under the careful guidance of the most famous mathematician at that time (John johann bernoulli, 1667- 1748).

Euler's profound knowledge, endless creative energy and unprecedented rich works are amazing! He published papers from the age of 19 to the age of 76, and has written countless books and papers for more than half a century. Up to now, Euler's name can be seen in almost every mathematical field, from Euler line of elementary geometry, euler theorem of polyhedron, Euler transformation formula of solid analytic geometry, Euler solution of quartic equation to Euler function in number theory, Euler equation of differential equation, Euler constant of series theory and Euler equation of variational method. Euler formula of complex variable function, etc. , is countless. His contribution to mathematical analysis is even more original. Introduction to infinitesimal analysis is his epoch-making masterpiece, and mathematicians call him "the embodiment of analysis" at that time.

Euler is the most prolific outstanding mathematician in the history of science. According to statistics, * * * has written 886 books and papers in his tireless life, of which 40% is analysis, algebra and number theory, 18% is geometry, 28% is physics and mechanics, 1 1% is astronomy, as well as ballistics and navigation.

The amazing productivity of Euler's works is not accidental. He can work in any harsh environment. He often holds his children on his knees to finish his papers, regardless of their noise. His indomitable perseverance and tireless academic spirit made him blind, and he didn't stop studying mathematics. During the 17 years after his blindness, he also dictated several books and about 400 papers. Gauss (1777- 1855), a great mathematician in the 9th century, once said, "Studying Euler's works is always the best way to understand mathematics."

Euler's father Paul Euler is also a mathematician. He wants little Euler to study theology and teach him a little at the same time. Because of his talent and extremely diligent spirit, he got johann bernoulli's appreciation and special guidance. When he was 19 years old, he wrote a paper on the mast and won a prize from the Paris Academy of Sciences. His father no longer opposed him to study mathematics.

Johann bernoulli's son daniel bernoulli went to Russia on 1725 and recommended Euler to czar Cadling I. In this way, Euler came to Petersburg on 17 and 1733. At the age of 26, Euler became a professor of mathematics at the Academy of Sciences in Petersburg. 1735, Euler solved a problem. It took several famous mathematicians several months to solve this problem, but Euler finished it in three days with his own invented method. However, due to overwork, he got an eye disease and unfortunately lost his right eye. At this time, he was only 28 years old. At the invitation of Prussian frederick the great, Euler went to Berlin as the director of the Institute of Physics and Mathematics of the Chinese Academy of Sciences until 1768. Later, at the sincere urging of Tsar Cadling II, he returned to Petersburg. Unexpectedly, not long after, his left eye vision decreased and he was completely blind. Unfortunately, the fire in Petersburg in 177 1 affected Euler's residence. 64-year-old Euler was blinded by illness and was trapped in the fire. Although he was saved from the fire by others, his research and a lot of research results were reduced to ashes.

The heavy blow still didn't knock Euler down. He vowed to recover the loss. Before he was completely blind, he could still see vaguely. He seized this last moment, scribbled down the formula he found on a big blackboard, and then dictated its contents, which were recorded by his students, especially his eldest son A. Euler (mathematician and physicist). After Euler was completely blind, he still struggled with the darkness with amazing perseverance and studied it with memory and mental arithmetic.

Euler's memory and mental arithmetic are rare. He can retell the contents of his notes when he was young. Mental arithmetic is not limited to simple operations, and advanced mathematics can also be done by heart. An example is enough to illustrate his skill. Two students of Euler added the term 17 of a complex convergence series to the 50th place, and the difference between them was one unit. In order to determine who is right, Euler calculated all the errors in his mind and finally put them into the errors. It also solved Newton's headache-the problem of starting from the moon and many complicated analysis problems.

Euler has a high style. Lagrange is a great mathematician after Euler. Since the age of 19, he has been communicating with Euler to discuss the general solution of isoperimetric problems, from which the variational method was born. The isoperimetric problem is a problem that Euler has painstakingly considered for many years. Lagrange's solution won warm praise from Euler. 1February 2, 759, Euler praised Lagrange's achievements in his reply. He modestly suppressed his immature works in this respect from being published for the time being, so that the works of young Lagrange could be published and circulated, and won great reputation. In his later years, all mathematicians in Europe regarded him as a teacher. The famous mathematician Laplace once said, "Euler is our mentor." Euler's energy was maintained until the last moment, in the afternoon of September 1783. In order to celebrate his successful calculation of the law of balloon rising, Euler invited friends to dinner. Soon after Uranus was discovered, Euler wrote the essentials of calculating Uranus' orbit and made fun of his grandson. After drinking tea, he suddenly fell ill, and his pipe fell out of his hand, muttering "I'm dead". Finally, Euler "stopped living and calculating".

Euler's life is a life of struggle for the development of mathematics. His outstanding wisdom, tenacious perseverance, tireless spirit of struggle and noble scientific ethics are always worth learning. Euler has made many achievements in mathematics, and the solution of the famous problem of the Seven Bridges in Konigsberg initiated the research of graph theory. Euler also found that no matter what shape of convex polyhedron, there is always a relationship between the number of vertices V, the number of edges E and the number of faces F, that is, v-e+f=2. V-e+f, which is called Euler characteristic, has become the basic concept of topology. In number theory, Euler first introduced the important Euler function φ(n), and proved Fermat's theorem in many ways. Mathematical formulas and theorems named after Euler can be found everywhere in mathematics books. At the same time, he has made brilliant achievements in physics, astronomy, architecture, music and philosophy. Euler also created many mathematical symbols, such as π( 1736), i( 1777), e (1748), sin and cos( 1748), tg( 1753).