Sharp estimates of the error of interpolation by bilinear splines for some classes of functions

On a two-point homogeneous space X, we consider the problem of describing the set of continuous functions having zero integrals over all spheres enclosing the given ball. We obtain the solution of this problem and its generalizations for an annular domain in X. By way of applications, we prove new uniqueness theorems for functions with zero spherical means.     

On interpolation of bilinear operators

In this paper we study interpolation of bilinear operators between products of Banach spaces generated by abstract methods of interpolation in the sense of Aronszajn and Gagliardo. A variant of bilinear interpolation theorem is proved for bilinear operators from corresponding weighted c₀ spaces into Banach spaces of non-trivial the periodic Fourier cotype. This result is then extended to the spaces generated by the well-known minimal and maximal methods of interpolation determined by quasi-concave functions. In the case when a maximal construction is generated by Hilbert spaces, we obtain a general variant of bilinear interpolation theorem. Combining this result with the abstract Grothendieck theorem of Pisier yields further results. The results are applied in deriving a bilinear interpolation theorem for Calderón-Lozanovsky, for Orlicz spaces and an embedding interpolation formula for (E,p)-summing operators.     

Shape-preserving interpolation by cubic splines

We consider the problem of shape-preserving interpolation by cubic splines. We propose a unified approach to the derivation of sufficient conditions for the k-monotonicity of splines (the preservation of the sign of any derivative) in interpolation of k-monotone data for k = 0, …, 4.     

Birkhoff interpolation by Chebyshevian splines

This paper deals with the interpolation of the function and its derivative values at scatted points, so-called Birkhoff Interpolation, by piecewise Chebyshevian spline. Research supported in part by NSERC Canada under Grant ≠A7687. This research formed part of a Thesis written for the Degree of Master of Science at the University of Alberta undr the supervision of Professor S.D. Riemenschneider.     

Numerical solution for fuzzy Fredholm integral equations with upper-bound on error by splines interpolation

In this paper, a numerical procedure is proposed for the fuzzy linear Fredholm integral equations of the second kind by using splines interpolation. Besides, the convergence conditions and an upper-bound on error are derived. Finally, the advantages of the proposed method have been shown through simulation examples and comparison with Lagrange method.     

A remark on interpolation by bivariate splines

We study the determining set for bivariate spline spacesS _k ^o on type-1 triangulation of square using B-net techniques. We further construct the interpolation schemes for these spline spaces that are unisolvent for any function f of C^σ.     

Extremal functional interpolation and approximation by splines

This article is the author's abstract of his dissertation for the degree Doctor of Physico-mathematical Science. The dissertation was defended on April 22, 1974 at the meeting of the Academic Council for the award of higher degrees in mathematics and mechanics at the Novosibirsk State University. Official opponents were: Academician N. N. Yanenko, Corresponding Member of the Academy of Sciences of the Ukrainian SSR, Doctor of Physicomathematical Sciences; Professor N. P. Korenchuk, Doctor of Physicomathematical Sciences; Professor G. Sh. Rubinshtein.Translated from Matematicheskie Zametki, Vol. 16, No. 5, pp. 843–854, November, 1974.     

Lagrange and hermite interpolation by bivariate splines

We develop methods for constructing sets of points which admit Lagrange and Hermite type interpolation by spaces of bivariate splines on rectangular and triangular partitions which are uniform, in general. These sets are generated by building up a net of lines and by placing points on these lines which satisfy interlacing properties for univariate spline spaces.     

Approximation and interpolation by convexity-preserving rational splines

A discussion and algorithm for combined interpolation and approximation by convexity-preserving rational splines is given.     

Shape-preserving interpolation by splines using vector subdivision

We give a local convexity preserving interpolation scheme using parametricC ² cubic splines with uniform knots produced by a vector subdivision scheme which simultaneously provides the function and its first and second order derivatives. This is also adapted to give a scheme which is both local convexity and local monotonicity preserving when the data values are strictly increasing in thex-direction.     

Constructing smooth interpolation splines

The authors present formulas for constructing continuous splines and smooth splines which are exact on any power of a given function.     

Construction of hyperbolic interpolation splines

The problem of constructing a hyperbolic interpolation spline can be formulated as a differential multipoint boundary value problem. Its discretization yields a linear system with a five-diagonal matrix, which may be ill-conditioned for unequally spaced data. It is shown that this system can be split into diagonally dominant tridiagonal systems, which are solved without computing hyperbolic functions and admit effective parallelization.     

Monotone and convex interpolation by weighted cubic splines

Algorithms for interpolating by weighted cubic splines are constructed with the aim of preserving the monotonicity and convexity of the original discrete data. The analysis performed in this paper makes it possible to develop two algorithms with the automatic choice of the shape-controlling parameters (weights). One of them preserves the monotonicity of the data, while the other preserves the convexity. Certain numerical results are presented.     

Lacunary interpolation by quartic splines on uniform meshes

The interpolation of a discrete set of data on the interval [0, 1], representing the first and the second derivatives (except at 0) of a smooth function f is investigated via quartic C²-splines. Error bounds in the uniform norm for ∥s⁽ⁱ⁾ − f⁽ⁱ⁾∥, i=0(1)2, if f ∈ C^l[0, 1], l=3, 5 and ⁽³⁾ ∈ BV[0, 1], together with computational examples will also be presented.     

Monotone and convex interpolation by weighted quadratic splines

In this paper we discuss the design of algorithms for interpolating discrete data by using weighted C ¹ quadratic splines in such a way that the monotonicity and convexity of the data are preserved. The analysis culminates in two algorithms with automatic selection of the shape control parameters: one to preserve the data monotonicity and other to retain the data convexity. Weighted C ¹ quadratic B-splines and control point approximation are also considered.