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Solving bordered linear systems
Štrausová, Jitka ; Janovský, Vladimír (advisor) ; Zítko, Jan (referee)
The comparison of two algorithms for solving bordered linear systems is considered. The matrix of this system consists of four blocks (matrices A,B,C,D), the upper left one is a sparse matrix A, which is ill-conditioned and structured. The other blocks (B,C,D) are dense. We say that the matrix A is bordered with the matrices B,C,D. It is desirable to preserve the block structure of the matrix and take advantage of sparsity and structure of the matrix A. The literature suggests to use two different algorithms: The first one is the method BEM for matrices with the borders of width equal to one. The recursive alternative for matrices with wider borders is called BEMW. The second algorithm is an iterative method. Both techniques are based on different variants of the block LU-decomposition.
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Overtaking model on a circular road
Krejčiřík, Radek ; Kofroň, Josef (referee) ; Janovský, Vladimír (advisor)
In this work we consider an extended follow-the-leader traffic model which was presented in [9]. The Model simulates movements of N identical cars on a circular road. There are two new aspects in this model included: velocity of each car depends on a variable reaction time and on an aggressiveness of the driver as well. Aggressiveness has a stabilizing effect on the traffic flow and variable reaction time changes the periodic dynamics in the model, but there are still some un-physical solutions. The benefit of this work is in an application of an overtaking-algorithm to the extended model. We also show an equivalent formulation of the problem as a system of ordinary differential equations with a discontinuous right-hand side. We show an existence of periodic solutions with overtaking.
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Matrix Pseudospectrum
Marková, Hana ; Najzar, Karel (referee) ; Janovský, Vladimír (advisor)
In the present work we study properties, calculation methods and behaviour of pseudospectrum of matrix or linear operator. First we introduce related terms, then we define pseudospectrum in four different ways and show its basic properties. Consequently, we generalize the theory of pseudospectrum for linear operators in Banach spaces. Basic methods of computation including fundamental possibilities of speeding up follow, but especially we go through computations on grid and path following technique. In the end we derive bounds which outline behaviour of dynamical systems. The last chapter contains practical example, which relates to laser theory.
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