%0 Journal Article %A Ortiz Herranz, Pedro %A Trillo Moya, Juan Carlos %T On the convexity preservation of a quasi C3 nonlinear interpolatory reconstruction operator on σ quasi-uniform grids %D 2021 %@ 2227-7390 %U http://hdl.handle.net/10317/10575 %X This paper is devoted to introducing a nonlinear reconstruction operator, the piecewise polynomial harmonic (PPH), on nonuniform grids. We define this operator and we study its main properties, such as its reproduction of second-degree polynomials, approximation order, and conditions for convexity preservation. In particular, for σ quasi-uniform grids with σ≤4, we get a quasi C3 reconstruction that maintains the convexity properties of the initial data. We give some numerical experiments regarding the approximation order and the convexity preservation. %K Matemática Aplicada %K Interpolation %K Reconstruction %K Nonlinearity %K Nonuniform %K σ quasi-uniform %K Convexity %K Class quasi C3 %K 12 Matemáticas %K 1206.07 Interpolación, Aproximación y Ajuste de Curvas %~ GOEDOC, SUB GOETTINGEN