Before performing the Propagation step of the simulation, you have the option of including
fast and slow diagnostics.
Fast diagnostics are enabled by default.
If either fast diagnostics or both fast and slow diagnostics are enabled, after Propagating,
the EME solver region object will return local diagnostics, coefficients, and global diagnostics
These results can be used to help troubleshoot which interfaces or regions of the device are causing problems
if the convergence testing results are not converging as expected.
Typically, the convergence tests described in the previous units are sufficient to get
It's only necessary to look at the error diagnostics results in more unusual situations.
We will focus on the local diagnostics and coefficients results, since these results
are the most intuitive, and they're also typically the most useful for troubleshooting.
If you want the detailed definitions of the results including global diagnostics results
that we're not going to cover here, see the link below this video.
Local diagnostics results include gain and loss, and the tangential field discontinuities.
The local gain and loss are the gain and loss due to the specified source that occurs along
the propagation axis, and it can be plotted as a function of the cell interface number,
or as a function of x position.
Gain and loss values are returned as a fraction of the power injected.
The tangential field discontinuities at each interface is given by the following equations
where EL and ER are the left and right fields at each interface and ES is the electric field
of the excitation source.
The coefficients result gives forward and backward propagating coefficients for each
mode in each cell for the given source excitation, which allows you to see which modes power
gets coupled into as it propagates.
In the next unit, we'll show how to use these results.