二维多项式拟合 仿照matlab中polyval编写

根据已知的三维离散数据（x,y,z）,在MATLAB中利用此函数进行三维曲面拟合，再根据polyval2d得出拟合函数的系数矩阵。-according to 3D discrete datum (x,y,z),use this function in MATLAB to fit 3D surface, and use polyval2d to get coefficient matrix

利用polyval2d函数可以得出polyfit2d拟合的三维曲面的函数的系数矩阵-use polyval2d function to get fit function created by polyfit2d coefficient matrix

利用polyval2d函数可以得出polyfit2d拟合的三维曲面的函数的系数矩阵-use polyval2d function to get fit function created by polyfit2d coefficient matrix