منابع مشابه
Which circulant preconditioner is better?
The eigenvalue clustering of matrices S−1 n An and C −1 n An is experimentally studied, where An, Sn and Cn respectively are Toeplitz matrices, Strang, and optimal circulant preconditioners generated by the Fourier expansion of a function f(x). Some illustrations are given to show how the clustering depends on the smoothness of f(x) and which preconditioner is preferable. An original technique ...
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Optimal preconditioners (those that provide a proper cluster at 1) are very important for the cg-like methods since they make them converge superlinearly. As is well known, for Toeplitz matrices generated by a continuous symbol, many circulant and circulant-like (related to different matrix algebras) preconditioners were proved to be optimal. In contrast, for multilevel Toeplitz matrices, there...
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The implicit finite difference scheme with the shifted Grünwald formula, which is unconditionally stable, is employed to discretize fractional diffusion equations. The resulting systems are Toeplitz-like and then the fast Fourier transform can be used to reduce the computational cost of the matrix-vector multiplication. The preconditioned conjugate gradient normal residual method with a circula...
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Background and Aims: The current study was conducted to compare the expression levels of collagen type Π and X during chondrogenesis of human adipose-derived mesenchymal stem cells (hADMSCs) pellet and micromass cultures. Materials and Methods: Extracted hADMSCs were cultured until three passages and then transferred to pellet and micromass cultures in the experimental groups of day 7 and day...
متن کاملWhich Methodology is Better for Combining Linear and Nonlinear Models for Time Series Forecasting?
Both theoretical and empirical findings have suggested that combining different models can be an effective way to improve the predictive performance of each individual model. It is especially occurred when the models in the ensemble are quite different. Hybrid techniques that decompose a time series into its linear and nonlinear components are one of the most important kinds of the hybrid model...
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ژورنال
عنوان ژورنال: Mathematics of Computation
سال: 1996
ISSN: 0025-5718
DOI: 10.1090/s0025-5718-96-00682-5