Restoring a simulation loads saved fields and material so that computation can continue from an earlier state. Fdtd_EzSimCreateFromCSV(path) creates a new simulation using the grid width recorded in the CSV file.
The loader restores the spatial step, Courant number, step counter, $E_z$, $H_y$, and material properties. Relative permittivity and permeability are converted back to absolute values. Update coefficients are recomputed from the restored material and discretization, rather than copied from the coefficient columns.
For example, this command advances a saved grid by another 100 steps:
$ dist/bin/fdtd \ --input-csv=simulation.csv \ --set-accel=openmp \ --add-wave \ --run=100 \ continued.csv
Sources must be registered again because callback functions and their parameters are not saved. Re-registering the original waveform lets it sample the restored counter; omitting it lets the existing fields evolve without further excitation.
The execution mode also starts from the default unless selected explicitly. The command-line driver preserves loaded conductivities unless a boundary option overrides them. --time-start can override the saved counter without clearing the restored fields.