%> The file <well.m> calculates the partial cross sections for a spherical%> square well potential of arbitrary strength, including arbitrary sign. %> V(r) =  V for  r < A, V = 0 for r > A.%> Choose A and V and the energy range.%> The partial cross sections and their sum are displayed as %> functions of wave number, then the differential cross section %> as a function of the scattering angle for a chosen energy %> Reference: Messiah Ch IX--X.%>%>