A computer program has been developed to analyze small angle neutron scattering (SANS) data by using the Debye method of spherical modification proposed by Glatter. In the calculational procedure the model shape is emulated with a large number of overlapping small spheres which fill the volume of the model shape. A technique is described for fitting experimental data to a resolution-broadened model scattering function. At each stage of the iterative procedure the radius of gyration is computed. The program is able to calculate the scattering function of the mixture of two different molecules. This facility even allows one to calculate the scattering function of the mixture of monomer and dimer of a particular molecule in aqueous solution. In case a portion of the molecule has a different weight from the rest, the program has a variation to calculate the scattering function of that model as well.