A finite-difference approach has been developed for precisely determining diffusion coefficient and T(1) relaxation time in fluid samples analyzed by magnetization-grating rotating-frame imaging (MAGROFI) with either a surface coil or a toroid cavity detector (TCD). This approach avoids shortcomings
Spectral and structural analysis of high precision finite difference matrices for elliptic operators
โ Scribed by Stefano Serra Capizzano; Cristina Tablino Possio
- Publisher
- Elsevier Science
- Year
- 1999
- Tongue
- English
- Weight
- 330 KB
- Volume
- 293
- Category
- Article
- ISSN
- 0024-3795
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โฆ Synopsis
In this paper we study the structural properties of matrices coming from high-precision Finite Dierence (FD) formulae, when discretizing elliptic (or semielliptic) differential operators vY u of the form
Strong relationships with Toeplitz structures and Linear Positive Operators (LPO) are highlighted. These results allow one to give a detailed analysis of the eigenvalues localisation/distribution of the arising matrices. The obtained spectral analysis is then used to deยฎne optimal Toeplitz preconditioners in a very compact and natural way and, in addition, to prove Szeg o-like and Widom-like ergodic theorems for the spectra of the related preconditioned matrices. A wide numerical experimentation, conยฎrming the theoretical results, is also reported.
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