| ¡@¡@Radial basis function (RBF) collocation method uses global shape functions to collocate for the approximate solution of PDE. It is a truly meshless method as compared to some of the meshless or element-free finite element methods. For the multiquadric and Gaussian RBFs, there are two ways to make the solution converge---either by refining the mesh size h, or by increasing the shape parameter c. While the h-scheme increases the computation cost, the c-scheme is done without extra cost. In this paper we establish by numerical experiment the exponential error estimate epsilon ~ O(lambda^{sqrt(c)/h}), where 0 < lambda < 1. We also propose the use of residual error as an error indicator to optimize the selection of c value. |