# Your first run

Channel: development; package: 2.0.0rc1; source: 2c32b7cf79b796fae825bfa08fc73d9914e61723

Page: https://remilab.ai/rfx/guide/first-run/
Source: https://github.com/bk-squared/rfx/blob/2c32b7cf79b796fae825bfa08fc73d9914e61723/docs/public/guide/first-run.mdx

A small closed metal box is a useful installation check. A short electric-current
pulse excites the field, the walls reflect it, and a probe records `Ez` over time.
There is no port or absorbing boundary in this model.

## Install and run

```bash
pip install rfx-fdtd
```

Select the documentation version matching your installation using the version
links above. For this development documentation, install the source revision
identified there if you need its exact API.

Copy the following into a Python file and run it. This block is generated from
the repository's `examples/quickstart/hello_world.py`; its builder and execution
are checked by the existing example tests.

```python
from rfx import GaussianPulse, Simulation

sim = Simulation(
    freq_max=10e9,
    domain=(0.02, 0.02, 0.02),
    dx=2e-3,
    boundary="pec",
)
sim.add_source(
    (0.01, 0.01, 0.01),
    "ez",
    waveform=GaussianPulse(f0=5e9, bandwidth=0.8),
    amplitude_kind="current",
)
sim.add_probe((0.014, 0.01, 0.01), "ez")

preflight = sim.preflight()
print(preflight.format())
preflight.raise_for_failure()
n_steps = 120
result = sim.run(n_steps=n_steps, compute_s_params=False)
print(result.time_series.shape)
```

## Read the result

The model is a 20 mm vacuum cube with perfectly conducting (PEC) walls and 2 mm
cells. Positions and dimensions are in metres. The waveform's centre frequency
is in hertz, and `amplitude_kind="current"` makes the excitation a current in amperes.

`result.time_series` has shape `(120, 1)`: one row per time step, one column per
probe. The probe is two cells away from the source. `result.dt` is the time
between rows. The pulse reflects in the lossless closed box, so continued
oscillation is expected; this is not an absorption or decay demonstration.

Preflight findings describe the model before it runs. Read warnings as well as
errors. Completing these 120 steps checks the installation and API use; it does
not establish an accurate resonance, Q, or a mesh-converged electromagnetic result.

## See what comes next

- [Visual manual](https://remilab.ai/rfx/gallery/visual-manual/): connect structures, field movies and measurements.
- [Quick start](https://remilab.ai/rfx/start/first-simulation/): add a material and absorbing boundaries, then record two probes.
- [Examples](https://remilab.ai/rfx/examples/): choose a runnable model for your application.