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Abel–Plana Formula
In mathematics, the Abel–Plana formula is a summation formula discovered independently by and . It states that :\sum_^\infty f(n)=\frac 1 2 f(0)+ \int_0^\infty f(x) \, dx+ i \int_0^\infty \frac \, dt. It holds for functions ''f'' that are holomorphic in the region Re(''z'') ≥ 0, and satisfy a suitable growth condition in this region; for example it is enough to assume that , ''f'', is bounded by ''C''/, ''z'', 1+ε in this region for some constants ''C'', ε > 0, though the formula also holds under much weaker bounds. . An example is provided by the Hurwitz zeta function, :\zeta(s,\alpha)= \sum_^\infty \frac = \frac + \frac 1 + 2\int_0^\infty\frac\frac, which holds for all s \in \mathbb, . Abel also gave the following variation for alternating sums: :\sum_^\infty (-1)^nf(n)= \frac f(0)+i \int_0^\infty \frac \, dt. Which is related to the Lindelöf summation formula \sum_^(-1)^kf(k)=(-1)^m\int_^f(m-1/2+ix)\frac Proof Let f be holomorphic on \Re(z ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Summation
In mathematics, summation is the addition of a sequence of any kind of numbers, called ''addends'' or ''summands''; the result is their ''sum'' or ''total''. Beside numbers, other types of values can be summed as well: functions, vectors, matrices, polynomials and, in general, elements of any type of mathematical objects on which an operation denoted "+" is defined. Summations of infinite sequences are called series. They involve the concept of limit, and are not considered in this article. The summation of an explicit sequence is denoted as a succession of additions. For example, summation of is denoted , and results in 9, that is, . Because addition is associative and commutative, there is no need of parentheses, and the result is the same irrespective of the order of the summands. Summation of a sequence of only one element results in this element itself. Summation of an empty sequence (a sequence with no elements), by convention, results in 0. Very often, the elements ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holomorphic Function
In mathematics, a holomorphic function is a complex-valued function of one or more complex variables that is complex differentiable in a neighbourhood of each point in a domain in complex coordinate space . The existence of a complex derivative in a neighbourhood is a very strong condition: it implies that a holomorphic function is infinitely differentiable and locally equal to its own Taylor series (''analytic''). Holomorphic functions are the central objects of study in complex analysis. Though the term ''analytic function'' is often used interchangeably with "holomorphic function", the word "analytic" is defined in a broader sense to denote any function (real, complex, or of more general type) that can be written as a convergent power series in a neighbourhood of each point in its domain. That all holomorphic functions are complex analytic functions, and vice versa, is a major theorem in complex analysis. Holomorphic functions are also sometimes referred to as ''regular fu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hurwitz Zeta Function
In mathematics, the Hurwitz zeta function is one of the many zeta functions. It is formally defined for complex variables with and by :\zeta(s,a) = \sum_^\infty \frac. This series is absolutely convergent for the given values of and and can be extended to a meromorphic function defined for all . The Riemann zeta function is . The Hurwitz zeta function is named after Adolf Hurwitz, who introduced it in 1882. Integral representation The Hurwitz zeta function has an integral representation :\zeta(s,a) = \frac \int_0^\infty \frac dx for \operatorname(s)>1 and \operatorname(a)>0. (This integral can be viewed as a Mellin transform.) The formula can be obtained, roughly, by writing :\zeta(s,a)\Gamma(s) = \sum_^\infty \frac \int_0^\infty x^s e^ \frac = \sum_^\infty \int_0^\infty y^s e^ \frac and then interchanging the sum and integral. The integral representation above can be converted to a contour integral representation :\zeta(s,a) = -\Gamma(1-s)\frac \int_C \frac dz where ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Residue Theorem
In complex analysis, the residue theorem, sometimes called Cauchy's residue theorem, is a powerful tool to evaluate line integrals of analytic functions over closed curves; it can often be used to compute real integrals and infinite series as well. It generalizes the Cauchy integral theorem and Cauchy's integral formula. From a geometrical perspective, it can be seen as a special case of the generalized Stokes' theorem. Statement The statement is as follows: Let be a simply connected open subset of the complex plane containing a finite list of points , , and a function defined and holomorphic on . Let be a closed rectifiable curve in , and denote the winding number of around by . The line integral of around is equal to times the sum of residues of at the points, each counted as many times as winds around the point: \oint_\gamma f(z)\, dz = 2\pi i \sum_^n \operatorname(\gamma, a_k) \operatorname( f, a_k ). If is a positively oriented simple closed curve, if i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cauchy Integral Theorem
In mathematics, the Cauchy integral theorem (also known as the Cauchy–Goursat theorem) in complex analysis, named after Augustin-Louis Cauchy (and Édouard Goursat), is an important statement about line integrals for holomorphic functions in the complex plane. Essentially, it says that if f(z) is holomorphic in a simply connected domain Ω, then for any simply closed contour C in Ω, that contour integral is zero. \int_C f(z)\,dz = 0. Statement Fundamental theorem for complex line integrals If is a holomorphic function on an open region , and \gamma is a curve in from z_0 to z_1 then, \int_f'(z) \, dz = f(z_1)-f(z_0). Also, when has a single-valued antiderivative in an open region , then the path integral \int_f'(z) \, dz is path independent for all paths in . Formulation on simply connected regions Let U \subseteq \Complex be a simply connected open set, and let f: U \to \Complex be a holomorphic function. Let \gamma: ,b\to U be a smooth closed curve. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Euler–Boole Summation
Euler–Boole summation is a method for summing alternating series based on Euler's polynomials, which are defined by : \frac=\sum_^\infty E_n(x)\frac. The concept is named after Leonhard Euler and George Boole. The periodic Euler functions are :\widetilde E_n(x+1)=-\widetilde E_n(x)\text \widetilde E_n(x)=E_n(x) \text 0 |
Results In Mathematics
''Results in Mathematics/Resultate der Mathematik'' is a peer-reviewed scientific journal that covers all aspects of pure and applied mathematics and is published by Birkhäuser. It was established in 1978 and the editor-in-chief is Catalin Badea (University of Lille). Abstracting and indexing This journal is abstracted and indexed by: * Science Citation Index Expanded * Mathematical Reviews * Scopus * ''Zentralblatt Math'' * Academic OneFile * Current Contents/Physical, Chemical and Earth Sciences * '' Mathematical Reviews'' According to the ''Journal Citation Reports'', the journal has a 2013 impact factor The impact factor (IF) or journal impact factor (JIF) of an academic journal is a scientometric index calculated by Clarivate that reflects the yearly mean number of citations of articles published in the last two years in a given journal, as ... of 0.642. References External links * {{Official website, https://www.springer.com/birkhauser/mathematics/jour ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
