forcing sim to work in 3D rather than 2D

[ptang314]

I'm running the posted example code for optical forces. I'm comparing my output (errors and all) with that of the posted jupyter notebook at https://github.com/NanoComp/meep/blob/master/python/examples/parallel-wvgs-force.ipynb The output that is shown on the example notebook Working in 3D dimensions. Computational cell is 7 x 5 x 0.0333333 with resolution 30 I copy and pasted the exact same code into my notebook, and confirmed the same behavior from terminal. In both situations I get the same error: RuntimeError: meep: Could not determine normal direction for given grid_volume. I noticed the initial output on my notebook and terminal a major difference: Working in 2D dimensions. Computational cell is 7 x 5 x 0 with resolution 30

I'm suspecting this is the reason why I'm getting the RuntimeError. How do I force my simulation to run in 3D rather than defaulting to 2D? I see in the example code the cell is defined as cell = mp.Vector3(sx+2dpml,sy+2dpml,0) Would this not force a 2D simulation since the 3rd dimension is 0?

Below is the entire traceback

RuntimeError Traceback (most recent call last)

in 7 8 for k in range(len(s)): ----> 9 fluxes_odd[k], forces_odd[k] = parallel_waveguide(s[k],True) 10 fluxes_even[k], forces_even[k] = parallel_waveguide(s[k],False) in parallel_waveguide(s, xodd) 82 wvg_force = sim.add_force(f, 0, 1, force_reg1, force_reg2) 83 ---> 84 sim.run(until_after_sources=500) 85 86 flux = mp.get_fluxes(wvg_flux)[0] ~/miniconda3/envs/mp/lib/python3.7/site-packages/meep/simulation.py in run(self, *step_funcs, **kwargs) 2283 2284 if self.fields is None: -> 2285 self.init_sim() 2286 2287 self._evaluate_dft_objects() ~/miniconda3/envs/mp/lib/python3.7/site-packages/meep/simulation.py in init_sim(self) 1335 1336 for s in self.sources: -> 1337 self.add_source(s) 1338 1339 for hook in self.init_sim_hooks: ~/miniconda3/envs/mp/lib/python3.7/site-packages/meep/simulation.py in add_source(self, src) 1597 if isinstance(src, EigenModeSource): 1598 if src.direction < 0: -> 1599 direction = self.fields.normal_direction(where) 1600 else: 1601 direction = src.direction ~/miniconda3/envs/mp/lib/python3.7/site-packages/meep/__init__.py in normal_direction(self, where) 4049 4050 def normal_direction(self, where): -> 4051 return _meep.fields_normal_direction(self, where) 4052 4053 def casimir_stress_dct_integral(self, dforce, dsource, mx, my, mz, ft, where, is_bloch=False): RuntimeError: meep: Could not determine normal direction for given grid_volume.

[oskooi]

This is a bug which is fixed by #1204.

[ptang314]

Thank you! I'll close this issue.