scholarly journals Convergence almost everywhere of multiple Fourier series over cubes

2017 ◽  
Vol 370 (3) ◽  
pp. 1629-1659
Author(s):  
Mieczysław Mastyło ◽  
Luis Rodríguez-Piazza
Keyword(s):  
Fourier Series ◽  
Multiple Fourier Series ◽  
Convergence Almost Everywhere ◽  
Almost Everywhere

STRUCTURAL AND GEOMETRIC CHARACTERISTICS OF SETS OF CONVERGENCE AND DIVERGENCE OF MULTIPLE FOURIER SERIES OF FUNCTIONS WHICH EQUAL ZERO ON SOME SET

2004 ◽  
Vol 02 (02) ◽  
pp. 187-195 ◽  
Author(s):  
I. L. BLOSHANSKII
Keyword(s):  
Fourier Series ◽  
Positive Measure ◽  
Linear Subspace ◽  
Multiple Fourier Series ◽  
Partial Sums ◽  
Geometric Characteristics ◽  
Convergence Almost Everywhere ◽  
Almost Everywhere ◽  
Dimensional Cube ◽  
Series Of Functions

Let E be an arbitrary set of positive measure in the N-dimensional cube TN=(-π,π)N⊂ℝN, N≥1, and let f(x)=0 on E. Let [Formula: see text] be some linear subspace of L1(TN). We investigate the behavior of rectangular partial sums of multiple trigonometric Fourier series of a function f on the sets E and TN\E depending on smoothness of the function f (i.e. of the space [Formula: see text]), and, as well, of structural and geometric characteristics of the set E (SGC(E)). Thus, we are describing pairs [Formula: see text]. It is convenient to formulate and investigate the posed question in terms of generalized localization almost everywhere (GL) and weak generalized localization almost everywhere (WGL). This means that for the multiple Fourier series of a function f, that equals zero on the set E, convergence almost everywhere is investigated on the set E (GL), or on some of its subsets E1⊂E, of positive measure (WGL).

scholarly journals Generalized localization for spherical partial sums of multiple Fourier series

2019 ◽  
Vol 489 (1) ◽  
pp. 7-10
Author(s):  
R. R. Ashurov
Keyword(s):  
Fourier Series ◽  
Multiple Fourier Series ◽  
Partial Sums ◽  
Localization Principle ◽  
Open Set ◽  
Almost Everywhere

In this paper the generalized localization principle for the spherical partial sums of the multiple Fourier series in the L2-class is proved, that is, if f L2 (ТN) and f = 0 on an open set ТN then it is shown that the spherical partial sums of this function converge to zero almost - ​everywhere on . It has been previously known that the generalized localization is not valid in Lp (TN) when 1 p 2. Thus the problem of generalized localization for the spherical partial sums is completely solved in Lp (TN), p 1: if p 2 then we have the generalized localization and if p 2, then the generalized localization fails.

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