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Harmonic analysis is a generalisation of Fourier analysis that studies the properties of functions. Check out this tag for abstract harmonic analysis (on abelian locally compact groups), or Euclidean harmonic analysis (eg, Littlewood-Paley theory, singular integrals). It also covers harmonic analysis on tube domains, as well as the study of eigenvalues and eigenvectors of the Laplacian on domains, manifolds and graphs.

1 vote
0 answers
189 views

Does the Total variation of the Fourier partial sum of a bv function with jumps converge to ...

Does the total variation of the Fourier partial sum of a piecewise continuous bv function converge to the total variation of the function as $N\to\infty$. To explain briefly, Let $f$ be a periodic B …
Rajesh D's user avatar
  • 698
4 votes
1 answer
486 views

What is the importance of convergence of variation of Fourier reconstruction to that of vari...

Let $f$ be a periodic function of bounded variation which jumps at a point $x_0\in\mathbb{R}$. Let $S_{N}[f]$ denote the partial Fourier sum of $f$ and let $C_{N}[f]$ denote the Cesaro partial sum. It …
Rajesh D's user avatar
  • 698
1 vote
1 answer
194 views

A metric on the set of BV functions, is it mentioned/studied in literature?

I'd like to propose the following metric which operates on the set $M$ of all square integrable functions that are also of bounded variation, of the form $f : (0,1) \to \mathbb{R}$. Given any $x,y \in …
Rajesh D's user avatar
  • 698
5 votes
3 answers
1k views

Property/Relations using Fourier series/transform, which give complete information about all...

Consider a function which has only jump singularities of the form of the function itself or one of its derivatives jumping. Now let $\hat{f}(k)$ be its Fourier transform/series. We know the decay of t …
Rajesh D's user avatar
  • 698
2 votes
0 answers
119 views

request for any expository works in pointwise convergence of double Fourier series and espec...

Quart. J. Math. Volume 37, Issue 1, Pages 53-79 On double Fourier series, and especially those which represent the double zeta-function with real and incommensurable parameters. Hardy, G.H. I am not …
Rajesh D's user avatar
  • 698
-1 votes
1 answer
1k views

A question about pointwise convergence of Fourier transform in $N$-dimensions

I am retreating back on this statement, after some explorations and calculation Bow to Willie and others who were skeptical on this. Main difficulty can be seen in this reference. But I must mention t …
Rajesh D's user avatar
  • 698
2 votes
0 answers
194 views

Shattering with sinusoids

Let $d \geq 2$ and $K$ some positive integer. Consider distinct points $\theta_1, \ldots, \theta_K\in \mathbb{T}^d$ and (not necessarily distinct) $z_1, \ldots, z_K \in \{-1,1\}$ such that $\sum\limit …
Rajesh D's user avatar
  • 698
1 vote
1 answer
816 views

What is the growth of sum of absolute values of Fourier coefficients

For a periodic BV function $f$ which has jump discontinuties, is there any theorem in Fourier analysis which gives like $$\sum_{k=0}^n\left|c_k\right|\sim C\log\left(n\right)$$ where $C$ is a constant …
Rajesh D's user avatar
  • 698
1 vote

Is this statement which relates the Fourier transform of a function to its singularities cor...

I would like to prove for the case of jump discontinuity of the function itself. (rather than that of one of its derivatives). Let $t_0>0$ be a point where $f$ jumps. The curve $$(X_{t_0}(s),Y_{t_0}( …
Rajesh D's user avatar
  • 698
3 votes
0 answers
214 views

Is flatness of Wigner Ville Distribution of error function in Fourier Approximation possible...

For a real valued function $f(t)$ I want to check the information left, after taking a Fourier partial sum/integral. Let $\hat{f}$ be its Fourier transform and let $$e_{\omega}(t) = f(t) - \int\limits …
Rajesh D's user avatar
  • 698
17 votes
2 answers
4k views

Is this statement which relates the Fourier transform of a function to its singularities cor...

I am working on a problem, which would possibly relate the Fourier transform/series with the jump singularities of the function where the function itself or one of its derivatives jump. ((some kind of …
Rajesh D's user avatar
  • 698