TimeEvolution input documentation
=================================


Initialize time evolution parameters


Used to initialize class :class:`qimpy.transport.TimeEvolution`.

YAML template:
--------------

.. parsed-literal::

   :yamlparam:`qimpy.transport.TimeEvolution:dt`: 0.0             :yamlcomment:`# Time step for evolution.`
   :yamlparam:`qimpy.transport.TimeEvolution:dt-save`: 0.0        :yamlcomment:`# Time interval at which to save results.`
   :yamlparam:`qimpy.transport.TimeEvolution:t-max`: 0.0          :yamlcomment:`# Stop evolution at this time.`
   :yamlparam:`qimpy.transport.TimeEvolution:n-collate`: 0        :yamlcomment:`# Number of save-steps to collect into each checkpoint file.`
   :yamlparam:`qimpy.transport.TimeEvolution:integrator`: RK2     :yamlcomment:`# Integrator for time-stepping: RK2 or RK4.`
   :yamlparam:`qimpy.transport.TimeEvolution:steady-state`: :yamlkey:`null`  :yamlcomment:`# Steady state options.`

Parameters:
-----------

dt
++

*Type:* :yamltype:`float`, *Default:*  0.0

Time step for evolution.
If zero, this is set to the maximum stable time step for advection.

dt-save
+++++++

*Type:* :yamltype:`float`, *Default:*  0.0

Time interval at which to save results.
This will be rounded to the nearest multiple of `dt` to ensure
that the results are written at uniform intervals.

t-max
+++++

*Type:* :yamltype:`float`, *Default:*  0.0

Stop evolution at this time.

n-collate
+++++++++

*Type:* :yamltype:`int`, *Default:*  0

Number of save-steps to collect into each checkpoint file.
Collecting together several saves can substantially improve performance
by amortizing the latency associated with disk I/O and GPU transfers.
The results in the checkpoint have an additional outermost dimension
corresponding to the number of collated steps.

integrator
++++++++++

*Type:* :yamltype:`string`, *Default:*  RK2

Integrator for time-stepping: RK2 or RK4.

steady-state
++++++++++++

*Type:* :yamltype:`string` or typing.Union[str, float], *Default:*  :yamlkey:`null`

Steady state options.
EXPERIMENTAL: works only with a single process and geometry domain for now.
Specify a dictionary of `rho0_path` for initial state, `method` for solver,
`nit` for number of iterations and `nit_save` for iterations to save at.