Nucleon-nucleon scattering analyses. III.npphase-shift analyses: Complex structure and multiple solutions at 50 and 325 MeV

Recent comprehensive analyses of $n-p$ data near 50 and 325 MeV reveal a complex ${\chi }^2$ hypersurface with nonquadratic behavior at 50 MeV and multiple minima at 325 MeV. We present the "most reasonable" solutions at these energies and present graphically some of the complex ${\chi }^2$ structure which invalidates the conventional measure of error on the resultant phase parameters.