By using a generalized Lorenz_Mie theory, the scattering field of spheres under Gaussian beams and plane_wave illumination is computed. The code is written with Matlab, and computational methods are improved. Computations for scattered fiel d in our code are extended to fairly large size parameters, up to 80000 The l ight scattering properties of absorbing and nonabsorbing homogeneous spherical p articles, coated spheres are investigated.