CAUCHY’S INTEGRAL THEOREM AND ITS CONSEQUENCES

2009 ◽  
pp. 436-442
Keyword(s):  
Integral Theorem ◽  
Cauchy’S Integral Theorem

scholarly journals An Efficient Method to Find Solutions for Transcendental Equations with Several Roots

2015 ◽  
Vol 2015 ◽  
pp. 1-4 ◽  
Author(s):  
Rogelio Luck ◽  
Gregory J. Zdaniuk ◽  
Heejin Cho
Keyword(s):  
Null Space ◽  
Heat Conduction Problem ◽  
Hankel Matrix ◽  
Polynomial Equation ◽  
Transient Heat Conduction ◽  
Transcendental Equation ◽  
Integral Theorem ◽  
Transient Heat Conduction Problem ◽  
Cauchy’S Integral Theorem ◽  
Roots Of A Polynomial

This paper presents a method for obtaining a solution for all the roots of a transcendental equation within a bounded region by finding a polynomial equation with the same roots as the transcendental equation. The proposed method is developed using Cauchy’s integral theorem for complex variables and transforms the problem of finding the roots of a transcendental equation into an equivalent problem of finding roots of a polynomial equation with exactly the same roots. The interesting result is that the coefficients of the polynomial form a vector which lies in the null space of a Hankel matrix made up of the Fourier series coefficients of the inverse of the original transcendental equation. Then the explicit solution can be readily obtained using the complex fast Fourier transform. To conclude, the authors present an example by solving for the first three eigenvalues of the 1D transient heat conduction problem.

scholarly journals An n-dimensional analogue of Cauchy's integral theorem

1960 ◽  
Vol 1 (2) ◽  
pp. 171-202 ◽  
Author(s):  
J. H. Michael
Keyword(s):  
Bounded Variation ◽  
Continuous Mapping ◽  
Topological Manifold ◽  
Parametric Surfaces ◽  
Integral Theorem ◽  
Cauchy’S Integral Theorem ◽  
Natural Way

As in [5] a parametric n-surface in Rk (where k ≧ n) will be a pair (f, Mn), consisting of a continuous mapping f of an oriented topological manifold Mn into the euclidean k-space Rk. (f, Mn) is said to be closed if Mn is compact. The main purpose of this paper is to use the method of [4] to prove a general form of Cauchy's Integral Theorem (Theorem 5.3) for those closed parametric n-surfaces (f, Mn) in Rn+1, which have bounded variation in the sense of [5] and for which f(Mn) has a finite Hausdorff n-measure. As in [4], the proof is carried out by approximating the surface with a simpler type of surface. However, when n > 1, a difficulty arises in that there are entities, which occur in a natural way, but are not parametric surfaces. We therefore introduce a concept which we call an S-system and which forms a generalisation (see 2.2) of the type of closed parametric n-surface that was studied in [5] II, 3 in connection with a proof of a Gauss-Green Theorem. The surfaces of [5] II, 3 include those that are studied in this paper.

scholarly journals From locality and unitarity to cosmological correlators

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
Sadra Jazayeri ◽  
Enrico Pajer ◽  
David Stefanyszyn
Keyword(s):  
Vacuum State ◽  
Tree Level ◽  
Local Theory ◽  
Optical Theorem ◽  
Translation Invariance ◽  
De Sitter ◽  
Integral Theorem ◽  
Vast Number ◽  
Time Translation ◽  
Cauchy’S Integral Theorem

Abstract In the standard approach to deriving inflationary predictions, we evolve a vacuum state in time according to the rules of a given model. Since the only observables are the future values of correlators and not their time evolution, this brings about a large degeneracy: a vast number of different models are mapped to the same minute number of observables. Furthermore, due to the lack of time-translation invariance, even tree-level calculations require an increasing number of nested integrals that quickly become intractable. Here we ask how much of the final observables can be “bootstrapped” directly from locality, unitarity and symmetries.To this end, we introduce two new “boostless” bootstrap tools to efficiently compute tree-level cosmological correlators/wavefunctions without any assumption about de Sitter boosts. The first is a Manifestly Local Test (MLT) that any n-point (wave)function of massless scalars or gravitons must satisfy if it is to arise from a manifestly local theory. When combined with a sub-set of the recently proposed Bootstrap Rules, this allows us to compute explicitly all bispectra to all orders in derivatives for a single scalar. Since we don’t invoke soft theorems, this can also be extended to multi-field inflation. The second is a partial energy recursion relation that allows us to compute exchange correlators. Combining a bespoke complex shift of the partial energies with Cauchy’s integral theorem and the Cosmological Optical Theorem, we fix exchange correlators up to a boundary term. The latter can be determined up to contact interactions using unitarity and manifest locality. As an illustration, we use these tools to bootstrap scalar inflationary trispectra due to graviton exchange and inflaton self-interactions.

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