Wavelet analysis
A refinement of Fourier analysis which enables to simplify the description of a complicated function in terms of a small number of coefficients. The formal history of wavelet theory began in the early 1980s when Jean Morlet, a French geophysicist, introduced the concept of wavelet and studied wavelet transform as a new tool for scientific signal analysis. In 1984, his collaboration with Alex Grossmann yielded a detailed mathematical study of the continuous wavelet transforms and their various applications. Although similar results had already been obtained 20-50 years earlier by several other researchers, the rediscovery of the old concepts provided a new method for decomposing functions.
Astrostatistics techniques