Abstract:In this paper, we study semi-Hyers–Ulam–Rassias stability and generalized semi-Hyers–Ulam–Rassias stability of differential equations x′t+xt−1=ft and x″t+x′t−1=ft,xt=0ift≤0, using the Laplace transform. Our results complete those obtained by S. M. Jung and J. Brzdek for the equation x′t+xt−1=0.
In this paper, on the basis of the Carleman matrix, we explicitly construct a regularized solution of the Cauchy problem for the matrix factorization of Helmholtz’s equation in an unbounded two-dimensional domain. The focus of this paper is on regularization formulas for solutions to the Cauchy problem. The question of the existence of a solution to the problem is not considered—it is assumed a priori. At the same time, it should be noted that any regularization formula leads to an approximate solution of the Cauchy problem for all data, even if there is no solution in the usual classical sense. Moreover, for explicit regularization formulas, one can indicate in what sense the approximate solution turns out to be optimal.
In this paper, on the basis of the Carleman matrix, we explicitly construct a regularized solution of the Cauchy problem for the matrix factorization of Helmholtz’s equation in an unbounded two-dimensional domain. The focus of this paper is on regularization formulas for solutions to the Cauchy problem. The question of the existence of a solution to the problem is not considered—it is assumed a priori. At the same time, it should be noted that any regularization formula leads to an approximate solution of the Cauchy problem for all data, even if there is no solution in the usual classical sense. Moreover, for explicit regularization formulas, one can indicate in what sense the approximate solution turns out to be optimal.
“…In [12], the Cauchy problem for the Helmholtz equation in an arbitrary bounded plane domain was considered. Certain boundary value problems and the determination of numerical solutions was investigated in [13][14][15][16][17][18][19][20][21][22][23][24][25]. In [21] is studied the Cauchy problem of a modified Helmholtz equation.…”
In this paper, using the construction of the Carleman matrix, we explicitly find a regularized solution of the Cauchy problem for matrix factorizations of the Helmholtz equation in a three-dimensional unbounded domain.
“…The field then continued to grow rapidly. We mention the works [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. A summary of certain works can be consulted in [20,21].…”
In this paper, we study Hyers–Ulam and generalized Hyers–Ulam–Rassias stability of a system of hyperbolic partial differential equations using Gronwall’s lemma and Perov’s theorem.
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