This paper deals with the topic of numerical integration on scattered data in Rd , d ≤ 10, by a class of spline functions, called Lobachevsky splines. Precisely, we propose new integration formulas based on Lobachevsky spline interpolants, which take advantage of being expressible in the multivariate setting as a product of univariate integrals. Theoretically, Lobachevsky spline integration for...

In this piece of work, using three spatial grid points, we discuss a new two-level implicit cubic spline method of O(k + kh + h) for the solution of quasi-linear parabolic equation   , , , , xx x t u f x t u u u  , 0< x <1, t > 0 subject to appropriate initial and Dirichlet boundary conditions, where h > 0, k > 0 are grid sizes in space and time-directions, respectively. The cubic spline app...

A new cubature rule for a parallelepiped domain is defined by integrating a discrete blending sum of C1 quadratic spline quasi-interpolants in one and two variables. We give the weights and the nodes of this cubature rule and we study the associated error estimates for smooth functions. We compare our method with cubature rules based on tensor products of spline quadratures and classical compos...

Quasi extended Chebyshev spaces (QEC-spaces for short) represent the largest class of spaces of sufficient regularity which are suitable for design [1]. In particular, they contain the well-known extended Chebyshev spaces as a special instance (and therefore can represent transcendental functions) as well as the so called variable degree polynomial spaces [2], that are very effective in handlin...

Quasi-interpolation is a well-known technique to construct accurate approximants to a given set of data or a given function by means of a local approach. A quasi-interpolant is usually obtained as a linear combination of a given system of blending functions that form a convex partition of unity and possess a small local support. These properties ensure both numerical stability and local control...

We study some C1 quadratic spline quasi-interpolants on bounded domains  ⊂ Rd, d = 1, 2, 3. These operators are of the form Q f (x) = ∑ k∈K () μk( f )Bk(x), where K () is the set of indices of B-splines Bk whose support is included in the domain  and μk( f ) is a discrete linear functional based on values of f in a neighbourhood of xk ∈ supp(Bk). The data points x j are vertices of a unifor...

Univariate and multivariate quadratic spline quasi-interpolants provide interesting approximation formulas for derivatives of approximated functions that can be very accurate at some points thanks to the superconvergence properties of these operators. Moreover, they also give rise to good global approximations of derivatives on the whole domain of definition. From these results, some collocatio...

The work of de Boor and Fix on spline approximation by quasiinterpolants has had far-reaching influence in approximation theory since publication of their paper in 1973. In this paper, we further develop their idea and investigate quasi-projection operators.We give sharp estimates in terms ofmoduli of smoothness for approximation with scaled shift-invariant spaces by means of quasi-projection o...