English

Inversion of $\alpha$-sine and $\alpha$-cosine transforms on $\mathbb{R}$

Functional Analysis 2021-07-13 v2 Numerical Analysis Numerical Analysis

Abstract

We consider the α\alpha-sine transform of the form Tαf(y)=0sin(xy)αf(x)dxT_\alpha f(y)=\int_0^\infty\vert\sin(xy)\vert^\alpha f(x)dx for α>1\alpha>-1, where ff is an integrable function on R+\mathbb{R}_+. First, the inversion of this transform for α>1\alpha>1 is discussed in the context of a more general family of integral transforms on the space of weighted, square-integrable functions on the positive real line. In an alternative approach, we show that the α\alpha-sine transform of a function ff admits a series representation for all α>1\alpha>-1, which involves the Fourier transform of ff and coefficients which can all be explicitly computed with the Gauss hypergeometric theorem. Based on this series representation we construct a system of linear equations whose solution is an approximation of the Fourier transform of ff at equidistant points. Sampling theory and Fourier inversion allow us to compute an estimate of ff from its α\alpha-sine transform. The same approach can be extended to a similar α\alpha-cosine transform on R+\mathbb{R}_+ for α>1\alpha>-1, and the two-dimensional spherical α\alpha-sine and cosine transforms for α>1\alpha>-1, α0,2,4,\alpha\neq 0,2,4,\dots. In an extensive numerical analysis, we consider a number of examples, and compare the inversion results of both methods presented.

Keywords

Cite

@article{arxiv.2103.17092,
  title  = {Inversion of $\alpha$-sine and $\alpha$-cosine transforms on $\mathbb{R}$},
  author = {Ly Viet Hoang and Evgeny Spodarev},
  journal= {arXiv preprint arXiv:2103.17092},
  year   = {2021}
}
R2 v1 2026-06-24T00:44:10.810Z