|
Cauchy's Limit Theorem
Cauchy's limit theorem, named after the French mathematician Augustin-Louis Cauchy, describes a property of converging sequences. It states that for a converging sequence the sequence of the arithmetic means of its first n members converges against the same limit as the original sequence, that is (a_n) with a_n\to a implies (a_1+\cdots+a_n) / n \ \to a.Konrad Knopp: ''Infinite Sequences and Series''. Dover, 1956, pp. 33-36Harro Heuser: ''Lehrbuch der Analysis – Teil 1'', 17th edition, Vieweg + Teubner 2009, ISBN 9783834807779, pp176-179(German) The theorem was found by Cauchy in 1821, subsequently a number of related and generalized results were published, in particular by Otto Stolz (1885) and Ernesto Cesàro (1888). Related results and generalizations If the arithmetic means in Cauchy's limit theorem are replaced by weighted arithmetic means those converge as well. More precisely for sequence (a_n) with a_n\to a and a sequence of positive real numbers (p_n) with \frac \to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Augustin-Louis Cauchy
Baron Augustin-Louis Cauchy ( , , ; ; 21 August 1789 – 23 May 1857) was a French mathematician, engineer, and physicist. He was one of the first to rigorously state and prove the key theorems of calculus (thereby creating real analysis), pioneered the field complex analysis, and the study of permutation groups in abstract algebra. Cauchy also contributed to a number of topics in mathematical physics, notably continuum mechanics. A profound mathematician, Cauchy had a great influence over his contemporaries and successors; Hans Freudenthal stated: : "More concepts and theorems have been named for Cauchy than for any other mathematician (in elasticity alone there are sixteen concepts and theorems named for Cauchy)." Cauchy was a prolific worker; he wrote approximately eight hundred research articles and five complete textbooks on a variety of topics in the fields of mathematics and mathematical physics. Biography Youth and education Cauchy was the son of Lou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Limit Of A Sequence
As the positive integer n becomes larger and larger, the value n\times \sin\left(\tfrac1\right) becomes arbitrarily close to 1. We say that "the limit of the sequence n \times \sin\left(\tfrac1\right) equals 1." In mathematics, the limit of a sequence is the value that the terms of a sequence "tend to", and is often denoted using the \lim symbol (e.g., \lim_a_n).Courant (1961), p. 29. If such a limit exists and is finite, the sequence is called convergent. A sequence that does not converge is said to be divergent. The limit of a sequence is said to be the fundamental notion on which the whole of mathematical analysis ultimately rests. Limits can be defined in any metric space, metric or topological space, but are usually first encountered in the real numbers. History The Greek philosopher Zeno of Elea is famous for formulating Zeno's paradoxes, paradoxes that involve limiting processes. Leucippus, Democritus, Antiphon (person), Antiphon, Eudoxus of Cnidus, Eudoxus, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arithmetic Mean
In mathematics and statistics, the arithmetic mean ( ), arithmetic average, or just the ''mean'' or ''average'' is the sum of a collection of numbers divided by the count of numbers in the collection. The collection is often a set of results from an experiment, an observational study, or a Survey (statistics), survey. The term "arithmetic mean" is preferred in some contexts in mathematics and statistics because it helps to distinguish it from other types of means, such as geometric mean, geometric and harmonic mean, harmonic. Arithmetic means are also frequently used in economics, anthropology, history, and almost every other academic field to some extent. For example, per capita income is the arithmetic average of the income of a nation's Human population, population. While the arithmetic mean is often used to report central tendency, central tendencies, it is not a robust statistic: it is greatly influenced by outliers (Value (mathematics), values much larger or smaller than ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Konrad Knopp
Konrad Hermann Theodor Knopp (22 July 1882 – 20 April 1957) was a German mathematician who worked on generalized limits and complex functions. Family and education Knopp was born in 1882 in Berlin to Paul Knopp (1845–1904), a businessman in manufacturing, and Helene (1857–1923), née Ostertun, whose own father was a butcher. Paul's hometown of Neustettin, then part of Germany, became Polish territory after the Second World War and is now called Szczecinek. In 1910, Konrad married the painter Gertrud Kressner (1879–1974). They had a daughter Ortrud Knopp (1911–1976), with the grandchildren Willfried Spohn (1944–2012), Herbert Spohn (born 1946) and Wolfgang Spohn (born 1950), and a son Ingolf Knopp (1915–2008), with the grandchildren Brigitte Knopp (born 1952) and Werner Knopp (born 1954). Konrad was primarily educated in Berlin, with a brief sojourn at the University of Lausanne in 1901 for a single semester, before settling at the University of Berlin, where he ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Harro Heuser
Harro Heuser (December 26, 1927 in Nastätten – February 21, 2011 in Bingen am Rhein, Bingen) was a Germans, German mathematician. In German-speaking countries he is best known for his popular two-volume introduction into real Mathematical analysis, analysis, ''Lehrbuch der Analysis''. Heuser studied mathematics, physics and philosophy from 1948 to 1954 at the University of Tübingen to receive a teaching degree (''Staatsexamen'') and went on to study for his PhD, which he received in 1957. The advisor of his thesis, entitled ''Über Operatoren mit endlichen Defekten'', was Helmut Wielandt. After receiving his PhD he moved to the University of Karlsruhe, where he received his habilitation in 1962. In 1963 he became a professor at the University of Kiel and in 1964 at the University of Mainz. Finally in spring 1969 he became a tenured professor at the University of Karlsruhe, where he remained until his retirement in 1996. He was also temporarily working as a visiting professor in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Otto Stolz
Otto Stolz (3 July 1842 – 23 November 1905) was an Austrian mathematician noted for his work on mathematical analysis and infinitesimals. Born in Hall in Tirol, he studied at the University of Innsbruck from 1860 and the University of Vienna from 1863, receiving his habilitation there in 1867. Two years later he studied in Berlin under Karl Weierstrass, Ernst Kummer and Leopold Kronecker, and in 1871 heard lectures in Göttingen by Alfred Clebsch and Felix Klein (with whom he would later correspond), before returning to Innsbruck permanently as a professor of mathematics. His work began with geometry (on which he wrote his thesis) but after the influence of Weierstrass it shifted to real analysis, and many small useful theorems are credited to him. For example, he proved that a continuous function ''f'' on a closed interval 'a'', ''b''with midpoint convexity, i.e., f\left(\frac2\right) \leq \frac, has left and right derivatives at each point in (''a'', ''b''). He died in 1905 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ernesto Cesàro
Ernesto Cesàro (12 March 1859 – 12 September 1906) was an Italian mathematician who worked in the field of differential geometry. He wrote a book, ''Lezioni di geometria intrinseca'' (Naples, 1890), on this topic, in which he also describes fractal, space-filling curves, partly covered by the larger class of de Rham curves, but are still known today in his honor as Cesàro curves. He is known also for his 'averaging' method for the 'Cesàro-summation' of divergent series, known as the Cesàro mean. Biography After a rather disappointing start of his academic career and a journey through Europe—with the most important stop at Liège, where his older brother Giuseppe Raimondo Pio Cesàro was teaching mineralogy at the local university—Ernesto Cesàro graduated from the University of Rome in 1887, while he was already part of the Royal Science Society of Belgium for the numerous works that he had already published. The following year, he obtained a mathematics chair at t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weighted Arithmetic Mean
The weighted arithmetic mean is similar to an ordinary arithmetic mean (the most common type of average), except that instead of each of the data points contributing equally to the final average, some data points contribute more than others. The notion of weighted mean plays a role in descriptive statistics and also occurs in a more general form in several other areas of mathematics. If all the weights are equal, then the weighted mean is the same as the arithmetic mean. While weighted means generally behave in a similar fashion to arithmetic means, they do have a few counterintuitive properties, as captured for instance in Simpson's paradox. Examples Basic example Given two school with 20 students, one with 30 test grades in each class as follows: :Morning class = :Afternoon class = The mean for the morning class is 80 and the mean of the afternoon class is 90. The unweighted mean of the two means is 85. However, this does not account for the difference in numbe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stolz–Cesàro Theorem
In mathematics, the Stolz–Cesàro theorem is a criterion for proving the convergence of a sequence. It is named after mathematicians Otto Stolz and Ernesto Cesàro, who stated and proved it for the first time. The Stolz–Cesàro theorem can be viewed as a generalization of the Cesàro mean, but also as a l'Hôpital's rule for sequences. Statement of the theorem for the case Let (a_n)_ and (b_n)_ be two sequences of real numbers. Assume that (b_n)_ is a strictly monotone and divergent sequence (i.e. strictly increasing and approaching + \infty , or strictly decreasing and approaching - \infty ) and the following limit exists: : \lim_ \frac=l.\ Then, the limit : \lim_ \frac=l.\ Statement of the theorem for the case Let (a_n)_ and (b_n)_ be two sequences of real numbers. Assume now that (a_n)\to 0 and (b_n)\to 0 while (b_n)_ is strictly decreasing. If : \lim_ \frac=l,\ then : \lim_ \frac=l.\ Proofs Proof of the theorem for the case Case 1: suppose (b_n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geometric Mean
In mathematics, the geometric mean is a mean or average which indicates a central tendency of a finite collection of positive real numbers by using the product of their values (as opposed to the arithmetic mean which uses their sum). The geometric mean of numbers is the Nth root, th root of their product (mathematics), product, i.e., for a collection of numbers , the geometric mean is defined as : \sqrt[n]. When the collection of numbers and their geometric mean are plotted in logarithmic scale, the geometric mean is transformed into an arithmetic mean, so the geometric mean can equivalently be calculated by taking the natural logarithm of each number, finding the arithmetic mean of the logarithms, and then returning the result to linear scale using the exponential function , :\sqrt[n] = \exp \left( \frac \right). The geometric mean of two numbers is the square root of their product, for example with numbers and the geometric mean is \textstyle \sqrt = The geometric mean o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Series (mathematics)
In mathematics, a series is, roughly speaking, an addition of Infinity, infinitely many Addition#Terms, terms, one after the other. The study of series is a major part of calculus and its generalization, mathematical analysis. Series are used in most areas of mathematics, even for studying finite structures in combinatorics through generating functions. The mathematical properties of infinite series make them widely applicable in other quantitative disciplines such as physics, computer science, statistics and finance. Among the Ancient Greece, Ancient Greeks, the idea that a potential infinity, potentially infinite summation could produce a finite result was considered paradoxical, most famously in Zeno's paradoxes. Nonetheless, infinite series were applied practically by Ancient Greek mathematicians including Archimedes, for instance in the Quadrature of the Parabola, quadrature of the parabola. The mathematical side of Zeno's paradoxes was resolved using the concept of a limit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
