We study numerical approximations of bifurcating solution curves of the von
Karman equations with simply supported and clamped boundary conditions, re
spectively. Of special interest here is the splitting of a double bifurcati
on point into two simple bifurcation points, and the tracing of the associa
ted secondary solution branches, which corresponds to the phenomenon of mod
e jumping in the buckling of a rectangular plate. A continuation-unsymmetri
c Lanczos algorithm is utilized for curve-tracking. Our numerical results v
erify the theoretical prediction of Schaeffer and Golubitsky, namely, mode
jumping occurs when the boundary is partially clamped, but not if it is mer
ely simply supported.