Starting from a saved interior field

A saved field can be the input to a new calculation beginning at its physical position inside a guide. Use this to compare response models over the same subsequent interval. A new segment records a new launch; continuing an interrupted calculation is instead described under file continuation.

Starting from an interior saved plane

An explicit modal spectrum can be launched at initial_z, in metres, while retaining the original guide length, absolute density and pressure profiles, propagation frame and coarse grid. The default is zero. A positive launch requires noise=None, no fixed schedule, and an array shaped (n_modes, n_pol, n_omega) in the internal FFT convention with true-power amplitudes. Every requested save must lie strictly beyond the launch, and the launch must precede the guide end.

To retain an existing simulation’s translated tables, use with_input:

from solprop.output import open_file

with open_file("parent.h5") as parent_output:
    plane_index = 10
    z_start = float(parent_output["z"][plane_index])
    spectrum = parent_output.fields(convention="fft")[plane_index]
    parent_hash = parent_output.metadata.configuration_hash()

segment = simulation.with_input(spectrum, initial_z=z_start, noise=None)
segment.run("segment.h5")

Here simulation is the matching parent configuration. An explicit initial_z filters its existing save planes to those strictly beyond the launch; omitting the keyword keeps the existing launch and saves. The new output includes the launch plane, and its metadata hashes the new input and launch coordinate. Normalisation uses the effective index at z_start, so a pressure gradient is sampled at the same physical position as the saved parent field. To change the response model, construct a new Simulation with the parent grid, modes, profiles and frame, the replacement responses, this spectrum and initial_z=z_start; include the parent hash and plane index in its configuration provenance and write a new output file.

The same continuation can be made through plane exchange, which checks the basis and records the provenance for you: couple(field_plane(parent_output, plane_index), simulation.input_port(z_start), model=CouplingModel("same_basis")).launch is a launch that simulation.with_input accepts, at z_start, with the parent named in configuration["coupling"] (coupling simulations).

For a TDSE response, SimulationSettings.tdse_execution explicitly selects the atomic runtime resources beside backend="numpy_ref" and a Multistep integrator. The declared response sampling refines the existing fine lattice once, retaining the coarse grid, period and collars. An inherited standard temporal collar is evaluated on the finer lattice with the same physical reference length; a custom absorber must already carry matching fine samples. Changing execution device, batch width or memory limits does not alter the scientific resume identity.