Relating smoothness to expressions involving Fourier coefficients or to a Fourier transform

Involving Fractional Fourier Transform

In this paper, some properties of pseudo-differential operators, SG-elliptic partial differential equations with polynomial coefficients and localization operators on space S ν (R), are studied by using fractional Fourier transform. AMS Mathematics Subject Classification (2010): 35S05, 46F12, 47G30.

Equivalence of K-functionals and modulus of smoothness for fourier transform

In Hilbert space L2(Rn), we prove the equivalence between the mod-ulus of smoothness and the K-functionals constructed by the Sobolev space cor-responding to the Fourier transform. For this purpose, Using a spherical meanoperator.

From Fourier Transform to Wavelets

Fourier Transform

Very broadly speaking, the Fourier transform is a systematic way to decompose “generic” functions into a superposition of “symmetric” functions. These symmetric functions are usually quite explicit (such as a trigonometric function sin(nx) or cos(nx)), and are often associated with physical concepts such as frequency or energy. What “symmetric” means here will be left vague, but it will usually...

A Fourier Transform

The harmonic function F exp(j2rvt) plays an important role in science and engineering. It has frequency v and complex amplitude F. Its real part IFIcos(2~vt + arg{F}) is a cosine function with amplitude jF( and phase arg{F}. The variable t usually represents time; the frequency v has units of cycles/s or Hz. The harmonic function is regarded as a building block from which other functions may be...