Fix two bugs in calculation of gamma0.

@Ternary_model/gamma0.m

 function g0 = gamma0(x, a, b, e_g0, u_g0, vt, e, u0)
 %GAMMA0 calculate spatially dependent mobility
 %   Based on a tanh profile.
-if isnumeric(isnumeric(e_g0))
+if isnumeric(e_g0)
     g0 = e_g0*(tanh((x+a+vt)/b)+1)/2+u_g0;
 else
-    g0 = u_g0./Ternary_model.phi_tot(x, a, b, e, u0, vt);
+    g0 = u_g0./(1-Ternary_model.phi_tot(x, a, b, e, u0, vt));
 end
 end
\ No newline at end of file