A procedure has been developed for the interpolation of functions defi
ned in two dimensions using the values of the function and its normal
derivatives at the boundary. The interpolating functions used are comb
inations of two classes of radial basis functions. This permits an int
erpolation scheme with osculatory features, i.e., the interpolant has
a specified slope at the boundary interpolation points. The improved a
ccuracy of the method is demonstrated over interpolation schemes using
the traditional radial basis functions (with no osculation), especial
ly for the calculation of the derivatives of the function at various i
nternal points. A brief discussion on the utility of the new interpola
tion technique in solving nonlinear Poisson problems using the dual re
ciprocity boundary element method is provided. (C) 1998 Elsevier Scien
ce Ltd. All rights reserved.