Resultants and contour integrals

Computation of contour integrals

The Analysis of Contour Integrals

Recommended by Stephen L. Clark For any n, the contour integral y cosh x ∮ C cosh zs / sinh z − sinhx n 1 dz, s2 −λ, is associated with differential equation d2y x /dx2 λ n n 1 /coshx y x 0. Explicit solutions for n 1 are obtained. For n 1, eigenvalues, eigenfunctions, spectral function, and eigenfunction expansions are explored. This differential equation which does have solution in terms of t...

Contour integrals associated differential equations

C cosh(zs) (sin z − sin x)n+1 dz, y = sinn+1 x ∮ C cosh(zs) (cos z − cos x)n+1 dz, s2 = −λ, and their associated second-order ordinary differential equationswhich are not studied are given. Complete solution is given by calculating residues for n = 1. The eigenvalues and eigenfunctions along with certain boundary conditions are explored for the first contour integral. The contour integral y(x) ...

Nonlinear eigenvalue problems and contour integrals

Beyn’s algorithm for solving nonlinear eigenvalue problems is given a new interpretation and a variant is designed in which the required information is extracted via the canonical polyadic decomposition of a Hankel tensor. A numerical example shows that the choice of the filter function is very important, particularly with respect to where it is positioned in the complex plane.

Numerical contour integration for loop integrals

A fully numerical method to calculate loop integrals, a numerical contour-integration method, is proposed. Loop integrals can be interpreted as a contour integral in a complex plane for an integrand with multi-poles in the plane. Stable and efficient numerical integrations an along appropriate contour can be performed for tensor integrals as well as for scalar ones appearing in loop calculation...