Vol 29, No 4 (2019)
- Year: 2019
- Articles: 3
- URL: https://journals.rcsi.science/1055-1344/issue/view/12235
Article
Shape-Preservation Conditions for Cubic Spline Interpolation
Abstract
We consider the problem on shape-preserving interpolation by classical cubic splines. Namely, we consider conditions guaranteeing that, for a positive function (or a function whose kth derivative is positive), the cubic spline (respectively, its kth derivative) is positive. We present a survey of known results, completely describe the cases in which boundary conditions are formulated in terms of the first derivative, and obtain similar results for the second derivative. We discuss in detail mathematical methods for obtaining sufficient conditions for shape-preserving interpolation. We also develop such methods, which allows us to obtain general conditions for a spline and its derivative to be positive. We prove that, for a strictly positive function (or a function whose derivative is positive), it is possible to find an interpolant of the same sign as the initial function (respectively, its derivative) by thickening the mesh.
Lie Type Jordan Algebras
Abstract
We study the variety νJ of Jordan algebras defined by the identities x2yx ≡ 0 and (x1y1)(x2y2)(x3y3) = 0. We suggest a method for constructing an algebra in νJ from an arbitrary Lie superalgebra. For certain subvarieties, we completely describe their identities and sequences of cocharacters. As a corollary, we obtain the first example of a variety of Jordan algebras with fractional exponential growth.