  One reports the integral transform that determines the particle size
distribution of a given sample from the small-angle scattering intensity under
the assumption that the particle correlation function is a polynomial of degree
M. The Fedorova-Schmidt solution [J. Appl. Cryst. 11, 405, (1978)] corresponds
to the case M = 3. The procedure for obtaining a polynomial approximation to a
particle correlation function is discussed and applied to the cases of
polidisperse particles of tetrahedral or octahedral or cubical shape.
