Fixed RK4.

src/maxwell_cpu.cpp

@@ -191,7 +191,7 @@ compute_euler_update(solver_state& state, const field& y, const field& k, double
 }
 
 void
-compute_rk4_weighted_sum(solver_state& state, const field& in, double dt, field out)
+compute_rk4_weighted_sum(solver_state& state, const field& in, double dt, field& out)
 {
     for (size_t i = 0; i < out.num_dofs; i++)
     {
@@ -224,10 +224,11 @@ timestep(solver_state& state)
     timecounter tc;
     tc.tic();
 
+    /*
     apply_operator(state, state.emf_curr, state.tmp);
     compute_euler_update(state, state.emf_curr, state.tmp, state.delta_t, state.emf_next);
+    */
 
-    /*
     apply_operator(state, state.emf_curr, state.k1);
 
     compute_euler_update(state, state.emf_curr, state.k1, 0.5*state.delta_t, state.tmp);
@@ -240,7 +241,7 @@ timestep(solver_state& state)
     apply_operator(state, state.tmp, state.k4);
 
     compute_rk4_weighted_sum(state, state.emf_curr, state.delta_t, state.emf_next);
-*/
+
     state.curr_time += state.delta_t;
     state.curr_timestep += 1;