Abstract:Abstract:In this paper, to overcome the innate drawbacks of some old methods, we present a new quintic spline method for integro interpolation. The method is free of any exact end conditions, and it can reconstruct a function and its first order to fifth order derivatives with high accuracy by only using the given integral values of the original function. The approximation properties of the obtained integro quintic spline are well studied and examined. The theoretical analysis and the numerical tests show that… Show more
“…To construct an integro-spline, we generally need n integral values I j ( j = 0, 1, • • •, n − 1) and several boundary conditions. In recent years, there are many studies about integro-spline interpolation ( [1,2,3,4,5,6,7,8,9,10,11,12]).…”
Section: The Authors and Ios Press This Article Is Published Online W...mentioning
In this paper, we construct a new kind of quartic integro-spline by applying two constraints on integral values to the piecewise polynomials on the first and the last subintervals, respectively. This quartic integro-spline does not require any additional given boundary values and is relatively simple to implement. It is theoretically proved that this integro-spline has a satisfactory convergence rate for approximating unknown functions and its derivatives at the knots. Especially for an unknown function y with fifth order derivative values of 0 at the left and right endpoints, its approximation of function values and second-order derivative values may even exhibit superconvergence at the knots. Numerical experiments have verified our theoretical results and compared the differences in approximation performance between our quartic integro-spline and other integro-splines.
“…To construct an integro-spline, we generally need n integral values I j ( j = 0, 1, • • •, n − 1) and several boundary conditions. In recent years, there are many studies about integro-spline interpolation ( [1,2,3,4,5,6,7,8,9,10,11,12]).…”
Section: The Authors and Ios Press This Article Is Published Online W...mentioning
In this paper, we construct a new kind of quartic integro-spline by applying two constraints on integral values to the piecewise polynomials on the first and the last subintervals, respectively. This quartic integro-spline does not require any additional given boundary values and is relatively simple to implement. It is theoretically proved that this integro-spline has a satisfactory convergence rate for approximating unknown functions and its derivatives at the knots. Especially for an unknown function y with fifth order derivative values of 0 at the left and right endpoints, its approximation of function values and second-order derivative values may even exhibit superconvergence at the knots. Numerical experiments have verified our theoretical results and compared the differences in approximation performance between our quartic integro-spline and other integro-splines.
“…In [8], it was proved that the super convergence (7) at the knots still hold even if the exact boundary function values y(x 0 ), y(x 1 ), y(x n−1 ), y(x n ) in (3), (4), ( 5) and ( 6) are replaced respectively by the approximate boundary function values y(x 0 ), y(x 1 ), y(x n−1 ), y(x n ) given in ( 8), ( 9), (10) and (11).…”
Section: Lemmamentioning
confidence: 99%
“…Approximating y = y(x) and its derivatives by using the integral values (1) is called integroapproximation. Splines have been widely used for this problem, see the works of Behforooz [1,2], Zhanlav [3][4][5], Mijiddorj [6,7], Lang [8][9][10], Xu [11,12], Haghighi [13,14], and Wu [15][16][17]. Generally, the obtained integro-splines have good approximation abilities.…”
Section: Introductionmentioning
confidence: 99%
“…Later, the super convergence of some other integro-splines at the knots of a uniform partition has also been studied. The super convergence of sextic integro-spline in approximating y (k) (x j ) (k = 0, 2, 4) was presented in [15] and the super convergence of quintic integro-spline in approximating y (k) (x j ) (k = 1, 3) was given in [3,9,10]. Do some integro-splines have super convergence properties at some other points?…”
In this paper, we study some new super convergence of a quartic integro-spline at the mid-knots of a uniform partition. We prove that the quartic integro-spline has super convergence in function values approximation (sixth order convergence), in second-order derivatives approximation (fourth order convergence) and in fourth-order derivatives approximation (second order convergence) at the mid-knots, no matter that the quartic integro-spline is determined by using four exact boundary conditions or is determined by using four approximate boundary conditions. These new super convergence properties also have been numerically examined.
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