Выдающаяся роль Леонарда Эйлера в развитии алгебры, геометрии и теории чисел - Дипломная работа

В первой главе представлено описание основных моментов жизни, повлиявших на творчество и развитие Леонарда Эйлера как крупного ученого и просветителя того времени. Paul Euler had studied theology at the University of Basel and had attended Jacob Bernoulli "s lectures there. Paul Euler had, as we have mentioned, some mathematical training and he was able to teach his son elementary mathematics along with other subjects. He had studied many mathematical works during his time in Basel, and Calinger [4] has reconstructed many of the works that Euler read with the advice of Johann Bernoulli . He wanted time to study the topics relating to his new post but also he had a chance of a post at the University of Basel since the professor of physics there had died.Декартом в первой половине XVII в., правда все предложенные ими формулировки сильно отличались от современной: Жирар утверждал, что уравнение степени n должно иметь ровно п корней, действительных или воображаемых, причем смысл последнего термина не уточнялся. Декарт лишь высказал лишь предложение: алгебраическое уравнение может иметь столько корней, какова его степень. Маклорен и Эйлер дали основной теореме формулировку, эквивалентную современной: всякое уравнение с действительными коэффициентами можно разложить в произведение множителей 1-й и 2-й степени с действительными коэффициентами, иными словами, уравнение степени п имеет п корней, действительных и комплексных. Работа Эйлера «Исследования о воображаемых корнях уравнений» («Recherches sur les racines imaginares des equations»), в которой приводится доказательство основной теоремы алгебры, была опубликована в «Мемуарах» Берлинской академии наук за 1749 г. в 1751 г. Кроме того, в процессе доказательства Эйлер впервые применил методы исследования уравнений, которые позднее были развиты Лагранжем и стали основными в его работах, посвященных вопросу решения уравнений в радикалах, а затем вошли в качестве неотъемлемой составной части в теорию Галуа.Так как всякий рекуррентный ряд получается из развертывания рациональной дроби, то пусть эта дробь будет равна откуда получается рекуррентный ряд Когда они найдены, то общий член рекуррентного ряда будет равен примем его равным Pzn; значит, P будет коэффициентом степени zn; у следующих же членов пусть коэффициенты будут Q, R, и т.д., так что рекуррентный ряд будет Теперь положим, что п представляет чрезвычайно большое число, т.е. что рекуррентный ряд продолжен весьма далеко; так как степени неравных чисел тем более отличаются друг от друга, чем они больше, тем между степенями и т.д. будет такое различие, что степень, соответствующая наибольшему из чисел р, q, r и т.д. между собой не равны, то пусть p будет наибольшим среди них. Итак, если у данной дроби в знаменателе все сомножители простые, действительные и не равные между собой, то из получающегося отсюда рекуррентного ряда можно будет узнать один простой множитель, именно, 1-pz, в котором буква р имеет самое большое значение. Верное же значение р обнаружится лишь тогда, когда ряд будет продолжен до бесконечности; когда получены уже многие его члены, то значение p найдется тем ближе, чем больше число членов и чем более буква р превосходит остальные q, r, s и т.д.; при этом безразлично, будет ли эта буква р сопровождаться знаком плюс или минус, так как степени ее возрастают одинаково.Долгое время великие математики пытались решить уравнения выше четвертой степени. Их неудачи не смогли поколебать убеждения математиков XVIII столетия о разрешимости всех алгебраических уравнений в обыкновенных иррациональностях. Он указывал, что решение уравнений второй, третьей и четвертой степеней приводится к уравнениям соответственно первой, второй и третьей степени; эти последние уравнения он называл «aequatio resolvens» («разрешающее уравнение»), откуда и возникло слово «резольвента». Эйлеру удалось образовать резольвенту уравнения третьей степени х3=ах b с помощью подстановки а уравнения четвертой степени x4=ax2 bx c с помощью подстановок или х= На этом основании он счел правомерным заключить, что, по всей вероятности, и для уравнения должна существовать резольвента (п-1)-й степени, определить которую следует посредством подстановки х= , Но уже при n=5 попытка, естественно, окончилась неудачей.Геометрическим работам Эйлера отведено пять томов первой серии Opera omnia.Следует упомянуть, что для де-Гюа было вполне привычным представление о кривой, распадающейся на несколько других, т. е. кривой, уравнение которой в левой части разлагается на ряд множителей. Эйлер целиком еще держался декартова понятия о координатах, между тем как Крамер, на сочинение которого книга Эйлера повлиять уже не могла, впервые равноправно определил две координаты и последовательно ввел ось ординат. Хотя вначале Эйлер определенно заявляет, что из одного принципа вывести все свойства конических сечений нельзя и что одни получаются из способа образования этих линий на конусе, а другие из приемов их описания, но здесь он желает опираться только на урав

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Введение. 3

Chapter I. Biography of Leonard Euler. 5

Глава II. Вклад Эйлера в развитие алгебры. 13

§2.1. Алгебраические доказательства основной теоремы алгебры. 13

§2.2 Числовые приближенные методы решения уравнений. 16 п.2.2.1. Метод рекуррентных рядов. 16 п.2.2.2. Еще два оригинальных метода. 19

§2.3. Общая теория уравнений. 21

Глава III. Выдающиеся достижения Леонарда Эйлера в области геометрии и тригонометрия. 23

§3.1. Развитие аналитической геометрии, начиная с систематического исследования высших порядков. 23

§3. 2. Поверхности второго и высших порядков. 28

§3.3. Второй том «введения в анализ бесконечных» 33

§3.4. Специальные плоские кривые. 38

§3.5. Геодезические линии 39

§3.6. Общие пространственные кривые и развертывающиеся поверхности 42

§3.7. Общие поверхности 45

§3.8. Заслуги Эйлера в преобразовании и дальнейших успехах тригонометрии. 52

ГЛАВА IV. Влияние Леонарда Эйлера на развитие теории чисел. 58

§4.1. Целочисленное решение неопределенных уравнений. 58

§4.2. Теорема Эйлера. 62

§4.3. Вычеты . 63

§4.4. Разложение на простые множители. 64

Заключение. 68

Список литературы. 69

Математика есть самая удивительная и загадочная сфера деятельности человеческой мысли. Развитие области фундаментальных знаний исторически неотъемлемо связано с развитием человеческого социума. Это значит, что основные грандиозные вехи развития этой изящной науки связаны с жизнью, без сомнения, гениальных умов человечества. В пантеон бессмертия выписаны имена математиков, чьи титанические труды обогатили людские знания всесущей.

Настоящая работа посвящена освещению биографии великого Леонарда Эйлера и его трудов, привнесших огромный вклад в развитие математики, и, прежде всего, в приложении ее к практической деятельности.

Необыкновенная интуиция, точный и искусный ум вели Леонарда Эйлера к изящным и удивительным открытиям, ныне кажущиеся столь простыми и естественными, что не вызывают никакого сомнения в их неприкасаемой правоте. В настоящее время многочисленные отрасли математики, механики, физики, астрономии до сих пор используют научные достижения трудов Эйлера, признанные, как основополагающие.

В первой главе представлено описание основных моментов жизни, повлиявших на творчество и развитие Леонарда Эйлера как крупного ученого и просветителя того времени. Большинство источников о биографии и деятельности Леонарда Эйлера были переведены, в основном, с немецкого на английский и французские языки, в частности, и на русский. В виду целесообразности первая глава представлена на английском языке, дабы быть ближе к первоисточникам.

Вторая глава повествует о существенном вкладе таланта Леонарда Эйлера в развитие алгебры XVIII столетия. В ней представлена работа, связанная с доказательством основной теоремы алгебры и методах приближенных решений алгебраических уравнений п-ой степени.

Третья глава посвящена выдающимся достижениям Леонарда Эйлера в области геометрии и тригонометрии. В нее включены работы по исследованию поверхностей второго и высших порядков, а так же специальных плоских кривых и геодезических линий. Леонард Эйлер написал первый систематизированный учебник по геометрии, общепризнанный классическим. Это второй том «Введения в анализ бесконечно малых». В данном учебнике развит единый метод для классификации плоских алгебраических кривых любого порядка и систематизированы практически все общие методы исследования таких кривых.

Четвертая глава повествует о крупнейших открытиях в теории диофантовых уравнений, занимавшей своей сложностью и изяществом прогрессивные умы математиков многих столетий. В XVIII веке Л. Эйлер, работая в Петербургской академии наук, издал большую часть своих работ по теории чисел и диофантовых уравнений. Он обобщил основной результат ферма для случая делимости на составные числа, создал общую теорию так называемых степенных вычетов, получил очень большое число разнообразных результатов о представимости чисел в виде форм определенного типа, исследовал ряд систем неопределенных уравнений и получил интересные результаты о разбиение чисел на слагаемые. У Эйлера мы впервые встречаемся с идеей применения методов математического анализа к задачам теории чисел. Рассмотрение бесконечных рядов и произведений являлось у Эйлера действенным орудием для получения теоретико-числовых результатов.

Нет, пожалуй, ни одной значительной области математики, в которой не оставил бы след один из величайших математиков 18 столетия Леонард Эйлер, чья жизнь и работа стимулируют творчество многие поколения математиков.

Chapter I. Biography of Leonard Euler.

Pic. 1 (Poster of Eule)

Leonhard Euler"s father was Paul Euler. Paul Euler had studied theology at the University of Basel and had attended Jacob Bernoulli "s lectures there. In fact Paul Euler and Johann Bernoulli had both lived in Jacob Bernoulli "s house while undergraduates at Basel. Paul Euler became a Protestant minister and married Margaret Brucker, the daughter of another Protestant minister. Their son Leonhard Euler was born in Basel, but the family moved to Riehen when he was one year old and it was in Riehen, not far from Basel, that Leonard was brought up. Paul Euler had, as we have mentioned, some mathematical training and he was able to teach his son elementary mathematics along with other subjects.

Leonhard was sent to school in Basel and during this time he lived with his grandmother on his mother"s side. This school was a rather poor one, by all accounts, and Euler learnt no mathematics at all from the school. However his interest in mathematics had certainly been sparked by his father"s teaching, and he read mathematics texts on his own and took some private lessons. Euler"s father wanted his son to follow him into the church and sent him to the University of Basel to prepare for the ministry. He entered the University in 1720, at the age of 14, first to obtain a general education before going on to more advanced studies. Johann Bernoulli soon discovered Euler"s great potential for mathematics in private tuition that Euler himself engineered. Euler"s own account given in his unpublished autobiographical writings, see [1] is as follows:-

... I soon found an opportunity to be introduced to a famous professor Johann Bernoulli . ... True, he was very busy and so refused flatly to give me private lessons; but he gave me much more valuable advice to start reading more difficult mathematical books on my own and to study them as diligently as I could; if I came across some obstacle or difficulty, I was given permission to visit him freely every Sunday afternoon and he kindly explained to me everything I could not understand ...

In 1723 Euler completed his Master"s degree in philosophy having compared and contrasted the philosophical ideas of Descartes and Newton . He began his study of theology in the autumn of 1723, following his father"s wishes, but, although he was to be a devout Christian all his life, he could not find the enthusiasm for the study of theology, Greek and Hebrew that he found in mathematics. Euler obtained his father"s consent to change to mathematics after Johann Bernoulli had used his persuasion. The fact that Euler"s father had been a friend of Johann Bernoulli "s in their undergraduate days undoubtedly made the task of persuasion much easier.

Euler completed his studies at the University of Basel in 1726. He had studied many mathematical works during his time in Basel, and Calinger [4] has reconstructed many of the works that Euler read with the advice of Johann Bernoulli . They include works by Varignon , Descartes , Newton , Galileo , von Schooten , Jacob Bernoulli , Hermann , Taylor and Wallis . By 1726 Euler had already a paper in print, a short article on isochronous curves in a resisting medium. In 1727 he published another article on reciprocal trajectories and submitted an entry for the 1727 Grand Prize of the Paris Academy on the best arrangement of masts on a ship.

The Prize of 1727 went to Bouguer , an expert on mathematics relating to ships, but Euler"s essay won him second place which was a fine achievement for the young graduate. However, Euler now had to find himself an academic appointment and when Nicolaus(II) Bernoulli died in St Petersburg in July 1726 creating a vacancy there, Euler was offered the post which would involve him in teaching applications of mathematics and mechanics to physiology. He accepted the post in November 1726 but stated that he did not want to travel to Russia until the spring of the following year. He had two reasons to delay. He wanted time to study the topics relating to his new post but also he had a chance of a post at the University of Basel since the professor of physics there had died. Euler wrote an article on acoustics, which went on to become a classic, in his bid for selection to the post but he was nor chosen to go forward to the stage where lots were drawn to make the final decision on who would fill the chair. Almost certainly his youth (he was 19 at the time) was against him. However Calinger [4] suggests:-

This decision ultimately benefited Euler, because it forced him to move from a small republic into a setting more adequate for his brilliant research and technological work.

As soon as he knew he would not be appointed to the chair of physics, Euler left Basel on 5 April 1727. He travelled down the Rhine by boat, crossed the German states by post wagon, then by boat from Lubeck arriving in St Petersburg on 17 May 1727. He had joined the St. Petersburg Academy of Science two years after it had been founded by Catherine I the wife of Peter the Great. Through the requests of Daniel Bernoulli and Jakob Hermann , Euler was appointed to the mathematical-physical division of the Academy rather than to the physiology post he had originally been offered. At St Petersburg Euler had many colleagues who would provide an exceptional environment for him [1]:-

Nowhere else could he have been surrounded by such a group of eminent scientists, including the analyst, geometer Jakob Hermann , a relative; Daniel Bernoulli , with whom Euler was connected not only by personal friendship but also by common interests in the field of applied mathematics; the versatile scholar Christian Goldbach , with whom Euler discussed numerous problems of analysis and the theory of numbers; F Maier, working in trigonometry; and the astronomer and geographer J-N Delisle.

Euler served as a medical lieutenant in the Russian navy from 1727 to 1730. In St Petersburg he lived with Daniel Bernoulli who, already unhappy in Russia, had requested that Euler bring him tea, coffee, brandy and other delicacies from Switzerland. Euler became professor of physics at the academy in 1730 and, since this allowed him to became a full member of the Academy, he was able to give up his Russian navy post.

Daniel Bernoulli held the senior chair in mathematics at the Academy but when he left St Petersburg to return to Basel in 1733 it was Euler who was appointed to this senior chair of mathematics. The financial improvement which came from this appointment allowed Euler to marry which he did on 7 January 1734, marrying Katharina Gsell, the daughter of a painter from the St Petersburg Gymnasium. Katharina, like Euler, was from a Swiss family. They had 13 children altogether although only five survived their infancy. Euler claimed that he made some of his greatest mathematical discoveries while holding a baby in his arms with other children playing round his feet.

We will examine Euler"s mathematical achievements later in this diploma but at this stage it is worth summarising Euler"s work in this period of his career. This is done in [4] as follows:-

... after 1730 he carried out state projects dealing with cartography, science education, magnetism, fire engines, machines, and ship building. ... The core of his research program was now set in place: number theory ; infinitary analysis including its emerging branches, differential equations and the calculus of variations ; and rational mechanics. He viewed these three fields as intimately interconnected. Studies of number theory were vital to the foundations of calculus, and special functions and differential equations were essential to rational mechanics, which supplied concrete problems.

The publication of many articles and his book Mechanica (1736-37), which extensively presented Newtonian dynamics in the form of mathematical analysis for the first time, started Euler on the way to major mathematical work.

Euler"s health problems began in 1735 when he had a severe fever and almost lost his life. However, he kept this news from his parents and members of the Bernoulli family back in Basel until he had recovered. In his autobiographical writings Euler says that his eyesight problems began in 1738 with overstrain due to his cartographic work and that by 1740 he had [4]:-

... lost an eye and [the other] currently may be in the same danger.

However, Calinger in [4] argues that Euler"s eyesight problems almost certainly started earlier and that the severe fever of 1735 was a symptom of the eyestrain. He also argues that a portrait of Euler from 1753 suggests that by that stage the sight of his left eye was still good while that of his right eye was poor but not completely blind. Calinger suggests that Euler"s left eye became blind from a later cataract rather than eyestrain.

By 1740 Euler had a very high reputation, having won the Grand Prize of the Paris Academy in 1738 and 1740. On both occasions he shared the first prize with others. Euler"s reputation was to bring an offer to go to Berlin, but at first he preferred to remain in St Petersburg. However political turmoil in Russia made the position of foreigners particularly difficult and contributed to Euler changing his mind. Accepting an improved offer Euler, at the invitation of Frederick the Great, went to Berlin where an Academy of Science was planned to replace the Society of Sciences. He left St Petersburg on 19 June 1741, arriving in Berlin on 25 July. In a letter to a friend Euler wrote:-

I can do just what I wish [in my research] ... The king calls me his professor, and I think I am the happiest man in the world.

Even while in Berlin Euler continued to receive part of his salary from Russia. For this remuneration he bought books and instruments for the St Petersburg Academy, he continued to write scientific reports for them, and he educated young Russians.

Maupertuis was the president of the Berlin Academy when it was founded in 1744 with Euler as director of mathematics. He deputised for Maupertuis in his absence and the two became great friends. Euler undertook an unbelievable amount of work for the Academy [1]:-

... he supervised the observatory and the botanical gardens; selected the personnel; oversaw various financial matters; and, in particular, managed the publication of various calendars and geographical maps, the sale of which was a source of income for the Academy. The king also charged Euler with practical problems, such as the project in 1749 of correcting the level of the Finow Canal ... At that time he also supervised the work on pumps and pipes of the hydraulic system at Sans Souci, the royal summer residence.

This was not the limit of his duties by any means. He served on the committee of the Academy dealing with the library and of scientific publications. He served as an advisor to the government on state lotteries, insurance, annuities and pensions and artillery. On top of this his scientific output during this period was phenomenal.

During the twenty-five years spent in Berlin, Euler wrote around 380 articles. He wrote books on the calculus of variations; on the calculation of planetary orbits; on artillery and ballistics (extending the book by Robins ); on analysis; on shipbuilding and navigation; on the motion of the moon; lectures on the differential calculus; and a popular scientific publication Letters to a Princess of Germany (3 vols., 1768-72).

In 1759 Maupertuis died and Euler assumed the leadership of the Berlin Academy, although not the title of President. The king was in overall charge and Euler was not now on good terms with Frederick despite the early good favour. Euler, who had argued with d"Alembert on scientific matters, was disturbed when Frederick offered d"Alembert the presidency of the Academy in 1763. However d"Alembert refused to move to Berlin but Frederick"s continued interference with the running of the Academy made Euler decide that the time had come to leave.

In 1766 Euler returned to St Petersburg and Frederick was greatly angered at his departure. Soon after his return to Russia, Euler became almost entirely blind after an illness. In 1771 his home was destroyed by fire and he was able to save only himself and his mathematical manuscripts. A cataract operation shortly after the fire, still in 1771, restored his sight for a few days but Euler seems to have failed to take the necessary care of himself and he became totally blind. Because of his remarkable memory was able to continue with his work on optics, algebra, and lunar motion. Amazingly after his return to St Petersburg (when Euler was 59) he produced almost half his total works despite the total blindness.

Euler of course did not achieve this remarkable level of output without help. He was helped by his sons, Johann Albrecht Euler who was appointed to the chair of physics at the Academy in St Petersburg in 1766 (becoming its secretary in 1769) and Christoph Euler who had a military career. Euler was also helped by two other members of the Academy, W L Krafft and A J Lexell , and the young mathematician N Fuss who was invited to the Academy from Switzerland in 1772. Fuss , who was Euler"s grandson-in-law, became his assistant in 1776. Yushkevich writes in [1]:-

… the scientists assisting Euler were not mere secretaries; he discussed the general scheme of the works with them, and they developed his ideas, calculating tables, and sometimes compiled examples.

For example Euler credits Albrecht, Krafft and Lexell for their help with his 775 page work on the motion of the moon, published in 1772. Fuss helped Euler prepare over 250 articles for publication over a period on about seven years in which he acted as Euler"s assistant, including an important work on insurance, which was published in 1776.

Yushkevich describes the day of Euler"s death in [1]:-

On 18 September 1783 Euler spent the first half of the day as usual. He gave a mathematics lesson to one of his grandchildren, did some calculations with chalk on two boards on the motion of balloons; then discussed with Lexell and Fuss the recently discovered planet Uranus. About five o"clock in the afternoon he suffered a brain hemorrhage and uttered only "I am dying" before he lost consciousness. He died about eleven o"clock in the evening.

After his death in 1783 the St Petersburg Academy continued to publish Euler"s unpublished work for nearly 50 more years.