On the representation of functions and finite difference operators on adaptive dyadic grids.
Let be a triangulation of a bounded polygonal domain , the space of the functions from linear on the triangles from and the interpolation operator from to . For a unit vector and an inner vertex of , we describe the set of vectors of coefficients such that the related linear combinations of the constant derivatives on the triangles surrounding are equal to for all polynomials of the total degree less than or equal to two. Then we prove that, generally, the values of the...
Sequences of cubature formulas with a joint countable set of nodes are studied. Each cubature formula under consideration has only a finite number of nonzero weights. We call a sequence of such kind a multicubature formula. For a given reflexive Banach space it is shown that there is a unique optimal multicubature formula and the sequence of the norm of optimal error functionals is monotonically decreasing to 0 as the number of the formula nodes tends to infinity.