In example 05 replace df["detector (E)" by df["detector (H)" generates exception RuntimeWarning

[GenB31415]

Hello to everybody. My question: I tried to execute your example "05. Lenses and analysing lensing actions" but with the use fdtd.dB_map_2D(df["detector (H)"]) in place of fdtd.dB_map_2D(df["detector (E)"]). The output shows
RuntimeWarning: invalid value encountered in scalar divide
a = 10 * log10([[y / minVal for y in x] for x in a]).
How to overcome this to see the structure of the magnetic field H? Thanks.

[GenB31415]

PS. I have converted your '05-lenses-and-analysing-lensing-actions.ipynb' to *.py script '05-lenses-and-analysing-lensing-actions.py'.