Radial Basis Function interpolation-RBF was originally developed for scattered multivariate data interpolation (Hardy 1971). It uses

a series of basis functions that are symmetric and centred at each sampling point. Radial basis

functions are a special class of functions with their main feature being that their response decreases

(or increases) monotonically with distance　a central point (Queipo et al. 2005). The centre, the

distance scale, and the precise shape of the radial function are parameters of the model. RBF

interpolation can be expressed as follows (Jin et al. 2002):