# An Integral Transformation and its Applications to Harmonic Analysis on the Space of Solutions of the Heat Equation

### Soon-Yeong Chung

Sogang University, Seoul, South Korea### Yongjin Yeom

Seoul National University, South Korea

## Abstract

We introduce an integral transformation *T* defined by

(*Tf*)(*x,t*) = ∫ *e_−_ixy_−_t*|*y*|2 *f*(*y*)*dy*, *f* ∈ *L_1(ℝ_n*)

in order to do harmonic analysis on the space of _C_∞ solutions of the heat equation.

First, the Paley–Wiener type theorem for the transformation *T* will be given for the _C_∞ functions and distributions with compact support.

Secondly, as an application of the transformation the solutions of heat equation given on the torus *T** will be characterized.

Finally, we represent solutions of the heat equation as an infinite series of Hermite temperatures, which are to be defined as the images of Hermite polynomials under the transformation *T*.

## Cite this article

Soon-Yeong Chung, Yongjin Yeom, An Integral Transformation and its Applications to Harmonic Analysis on the Space of Solutions of the Heat Equation. Publ. Res. Inst. Math. Sci. 35 (1999), no. 5, pp. 737–755

DOI 10.2977/PRIMS/1195143421