Shape preserving fractal multiquadric quasi-interpolation

In this article, we construct a novel self-referential fractal multiquadric function which is symmetric about the origin. The scaling factors are suitably restricted to preserve the differentiability and the convexity of the underlying classical multiquadric function. Based on the translates of a fractal multiquadric function defined on a grid, we propose two fractal quasi-interpolants \(L_C^{\alpha }f\) $L_C^{\alpha }f$ and \(L_D^{\alpha }f\) $L_D^{\alpha }f$ to approximate smooth and irregular functions. We study the convergence of \(L_C^{\alpha }f\) $L_C^{\alpha }f$ and \(L_D^{\alpha }f\) $L_D^{\alpha }f$ to f using uniform error estimates. We investigate the linear polynomial reproducing property, convexity/concavity and monotonicity features of these quasi-interpolation operators. The advantages of fractal quasi-interpolants over the classical quasi-interpolants are demonstrated by various examples.