Advanced configuration
======================

In :doc:`../setup/setup_conf`, we saw how to set some of the basic parameters that determine how Hyperion is run, and in this section we discuss some more advanced options.

Monochromatic radiative transfer
--------------------------------

.. note:: This section is being written

Scattered-light images
----------------------

In some cases, one might want to compute scattered light images at wavelengths where there is no dust emission. In this case, there is no need to compute the specific energy of the dust, and there is also no need in re-emitting photons when computing images/SEDs. Therefore, one can set::

    m.set_n_initial_iterations(0)
    m.set_kill_on_absorb(True)
    m.set_raytracing(True)

which turns off the specific energy calculation, kills photons as soon as they are first absorbed, and enables raytracing for the source emission. For the photon numbers, one can set ``raytracing_dust=0`` to zero, since this is not needed (there is no dust emission).

.. note:: This cannot be used for *all* scattered light images. For example,
          in a protostar, a K-band image may have a non-negligeable amount of
          scattered light flux originating from the inner rim of the disk.
          This technique can only be used when there is no dust emission.

Miscellaneous Settings
----------------------

Set the maximum number of photon interactions::

    m.set_max_interactions(100000)

Set the number of output bytes per floating point value for the physical
arrays (4 = 32-bit, 8 = 64-bit)::

    m.set_output_bytes(4)

To set the minimum temperature for dust::

    m.set_minimum_temperature(10.)
    m.set_minimum_temperature([10., 5., 20.])

If a scalar value is specified, the same value is used for all dust types. If
a list is specified, the list should have as many items as dust types, and
each item corresponds to the minimum temperature for each dust type.

Similarly, to set the minimum specific energy::

    m.set_minimum_specific_energy(1.e-4)
    m.set_minimum_specific_energy([1.e-4, 1.e-5, 2.e-5])

By default, photon positions and cells are double-checked every 1 in 1000 cell
crossings. This can be changed
with :meth:`~hyperion.model.Model.set_propagation_check_frequency`::

    m.set_propagation_check_frequency(0.01)

Note that values higher than 0.001 (the default) will cause the code to slow
down.