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arXiv · 1809.03808

A fast Fourier transform based direct solver for the Helmholtz problem

Jari Toivanen·Monika Wolfmayr
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Abstract

This paper is devoted to the efficient numerical solution of the Helmholtz equation in a two- or three-dimensional rectangular domain with an absorbing boundary condition (ABC). The Helmholtz problem is discretized by standard bilinear and trilinear finite elements on an orthogonal mesh yielding a separable system of linear equations. The main key to high performance is to employ the Fast Fourier transform (FFT) within a fast direct solver to solve the large separable systems. The computational complexity of the proposed FFT based direct solver is O(N log N) operations. Numerical results for both two- and three-dimensional problems are presented confirming the efficiency of the method discussed.

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Jari Toivanen, Monika Wolfmayr. 2018-09-11. A fast Fourier transform based direct solver for the Helmholtz problem. https://arxiv.org/abs/1809.03808

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