# Requirements¶

Warning

The radiative transfer schemes are still in development and are not useable at this moment. This page is currently a placeholder to document new features and requirements as the code grows.

To be able to run with radiative transfer, you’ll need to run swift with the following flags:

swift --radiation --hydro --feedback --stars --self-gravity [and/or] --external-gravity


Some notes:

• The radiation data is coupled to the gas data, so you can’t run without --hydro. (Also the whole point of these schemes is the interaction between gas and radiation, so why would you want to?)
• Currently the only source of radiation are stars, so you need --stars. If you want to run without radiative sources, still run the code with --stars, even if you don’t have any stars in your initial conditions.
• Running with --stars requires some form of gravity, be it self-gravity or external gravity. Since we need stars, we inherit this requirement. If you want no gravity, run with --external-gravity and set the external potential to zero.
• We need --feedback in order to have meaningful smoothing lengths for stars. However, you don’t need any specific feedback model; It’ll work even if you configured --with-feedback=none.