SOME ITERATIVE ALGORITHMS TO COMPUTE CANONICAL WINDOWS FOR GABOR FRAMES

Author(s):  
A. J. E. M. Janssen
Author(s):  
PETER BALAZS ◽  
JEAN-PIERRE ANTOINE ◽  
ANNA GRYBOŚ

Weighted and controlled frames have been introduced recently to improve the numerical efficiency of iterative algorithms for inverting the frame operator. In this paper, we develop systematically these notions, including their mutual relationship. We will show that controlled frames are equivalent to standard frames and so this concept gives a generalized way to check the frame condition, while offering a numerical advantage in the sense of preconditioning. Next, we investigate weighted frames, in particular their relation to controlled frames. We consider the special case of semi-normalized weights, where the concepts of weighted frames and standard frames are interchangeable. We also make the connection with frame multipliers. Finally, we analyze weighted frames numerically. First, we investigate three possibilities for finding weights in order to tighten a given frame, i.e. decrease the frame bound ratio. Then, we examine Gabor frames and how well the canonical dual of a weighted frame is approximated by the inversely weighted dual frame.


2002 ◽  
Vol 58 (9-10) ◽  
pp. 9
Author(s):  
Efim Grigor'evich Zelkin ◽  
Victor Filippovich Kravchenko ◽  
Miklhail Alekseevich Basarab

1989 ◽  
Author(s):  
SEUNGSOO LEE ◽  
GEORGE DULIKRAVICH ◽  
DANIEL DORNEY

Filomat ◽  
2017 ◽  
Vol 31 (12) ◽  
pp. 3611-3626 ◽  
Author(s):  
Abdul Khan ◽  
Vivek Kumar ◽  
Satish Narwal ◽  
Renu Chugh

Many popular iterative algorithms have been used to approximate fixed point of contractive type operators. We define the concept of generalized ?-weakly contractive random operator T on a separable Banach space and establish Bochner integrability of random fixed point and almost sure stability of T with respect to several random Kirk type algorithms. Examples are included to support new results and show their validity. Our work generalizes, improves and provides stochastic version of several earlier results by a number of researchers.


2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Adisorn Kittisopaporn ◽  
Pattrawut Chansangiam ◽  
Wicharn Lewkeeratiyutkul

AbstractWe derive an iterative procedure for solving a generalized Sylvester matrix equation $AXB+CXD = E$ A X B + C X D = E , where $A,B,C,D,E$ A , B , C , D , E are conforming rectangular matrices. Our algorithm is based on gradients and hierarchical identification principle. We convert the matrix iteration process to a first-order linear difference vector equation with matrix coefficient. The Banach contraction principle reveals that the sequence of approximated solutions converges to the exact solution for any initial matrix if and only if the convergence factor belongs to an open interval. The contraction principle also gives the convergence rate and the error analysis, governed by the spectral radius of the associated iteration matrix. We obtain the fastest convergence factor so that the spectral radius of the iteration matrix is minimized. In particular, we obtain iterative algorithms for the matrix equation $AXB=C$ A X B = C , the Sylvester equation, and the Kalman–Yakubovich equation. We give numerical experiments of the proposed algorithm to illustrate its applicability, effectiveness, and efficiency.


Methods ◽  
2021 ◽  
Author(s):  
Yatao Zhang ◽  
Zhenguo Ma ◽  
Jiarui Song ◽  
Xiaoming Kong ◽  
Ziyu Guo ◽  
...  
Keyword(s):  

2021 ◽  
Vol 47 (4) ◽  
Author(s):  
Ole Christensen ◽  
Say Song Goh ◽  
Hong Oh Kim ◽  
Rae Young Kim

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