Abstract: A bivariate rational biquartic interpolating spline based on function values with four parameters is constructed, and this spline is with biquartic numerator and biquadratic denominator. The interpolating function has a simple and explicit mathematical representation, which is convenient both in practical application and in theoretical study. The interpolating surface is C1 in the interpolating region when two of the parameters satisfiy a simple condition, when another two parameters are selected suitably, the interpolating function could be expressed in matrix form. The interpolating surface can be modified by selecting suitable parameters under the condition that the interpolating data are not changed. Some properties of the interpolation are derived.

Key words: computer application, bivariate interpolation, rational spline, computer aided geometric design