# Simulation state (1D FDTD)

The **simulation state** combines fields, material, coefficients, grid parameters, and sources. A reset deliberately clears only the advancing fields and clock:

```c
void Fdtd_EzSimReset(Fdtd_EzSim *sim)
{
    Fdtd_EzStateReset(sim->fsim_state);
    Fdtd_EzFieldsReset(sim->fsim_fields);
}
```

Material, coefficients, execution mode, and source registrations remain in place. This lets benchmark repetitions restart the same setup without reconstructing it.

In contrast, consecutive `Fdtd_EzSimRun(sim, nsteps)` calls continue from the current fields and step counter. `Fdtd_EzSimGetTime()` returns that counter, while `Fdtd_EzSimGetDt()` supplies seconds per step. [[fdtd-openmp-csv-output|CSV output]] saves fields and material for later restoration, but not source callbacks.

Source: [fdtd_ez_sim.c](https://github.com/yanevskiv/fdtd-openmp/blob/main/src/fdtd/Ez/fdtd_ez_sim.c).