Abstract: Surface fitting and software to scattered data are concerned.Some efficient algorithms are presented for interpolating and smoothing scattered data on two and three-dimensional domains by splines.The methods can be extended to any multi-dimensional cases and are easily performed on a computer by solving a symmetric linear algebraic system coefficient matrix,order of which is dependent on the number of the data and independent of the dimension of variables.The programs executing the algorithms are designed with Delphi 3^0.The software can output values on any points of the three-dimensional graph of the surface.Some numerical examples (graphs) illustrate the effectiveness of the software.

Key words: scattered data, fitting surface, spline interpolation, smooth approximation, minimization