Approximation spectral d'un opérateur borné et normal à l'aide de ses fonctions de la densité spectrale
In part II the author investigates the inner approximate representation of solutions of the equation F(x)=0 in the neighbourhood of regular and critical points.
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The contents of part I lie in the compilation of papers by Descloux and Rappaz ["On numerical approximation of solution branches of nonlinear equations'', École Polytech. Lausanne, Lausanne, 1981; per bibl.; RAIRO Anal. Numér. 16 (1982), no. 4, 319–349; MR0684829]. In Banach spaces the author investigates the implicit nonlinear operator equation F(x)=0 with a sufficiently smooth operator F. He formulates the notions of regular and critical points of an operator and studies the behaviour of the solutions...
The finite difference “box” scheme, (see also [1],[2]), is considered on the simplest possible model of single first order linear hyperbolic equation: ut+mux=0 with constant, coefficient m, and one space variable. The optimal version of the scheme, which is nonoscilating and unconditionally stable with respect to the initial and boundary conditions, is derived in the class of box schemes of the order at, least one. If apropriately iterated, this ścinane may be applied to general systems of quasilinear...
The author gives certain schemas of approximation to certain bounded linear operators in Banach spaces by means of families of simpler operators and of approximation to solutions of linear equations. Estimates of accuracy are given, which seem to be the main aim of the paper. The very technical character of the paper makes it impossible to give here a more detailed description of the contents.
For a large system of linear algebraic equations , the approximate solution is computed as the -th order Fourier development of the function , related to orthogonal polynomials in space. The domain in the complex plane is assumed to be known. This domain contains the spectrum of the matrix . Two algorithms for are discussed. Two possibilities of preconditioning by an application of the so called Richardson iteration process with a constant relaxation coefficient are proposed. The case...
Table des Matières§ 1. Généralités. Matrices infinies............................................ 5§ 2. Systèmes infinis d'équations différentielles. Problème de Cauchy. Existence-unicité............................................................................ 10§ 3. Approximation par les systèmes finis......................................... 20§ 4. Dépendance de la solution des conditions initiales ou d'un paramètre......... 23§ 5. Quelques remarques sur la séparation des variables..............................
The Jeffreys model of heat conduction is a system of two partial differential equations of mixed hyperbolic and parabolic character. The analysis of an initial-boundary value problem for this system is given. Existence and uniqueness of a weak solution of the problem under very weak regularity assumptions on the data is proved. A finite difference approximation of this problem is discussed as well. Stability and convergence of the discrete problem are proved.
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