From 04165f1818a2cda5d4acb0418a7de735c8f057a0 Mon Sep 17 00:00:00 2001 From: Matthieu Schaller <schaller@strw.leidenuniv.nl> Date: Fri, 8 Mar 2019 23:19:41 +0100 Subject: [PATCH] Document the behaviour of dt_min and dt_max in cosmological runs. --- doc/RTD/source/ParameterFiles/parameter_description.rst | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/doc/RTD/source/ParameterFiles/parameter_description.rst b/doc/RTD/source/ParameterFiles/parameter_description.rst index 207c173001..a415937763 100644 --- a/doc/RTD/source/ParameterFiles/parameter_description.rst +++ b/doc/RTD/source/ParameterFiles/parameter_description.rst @@ -269,7 +269,13 @@ time-step limited by the maximal value on top of all the other criteria that may apply to them (gravity acceleration, Courant condition, etc.). If a particle demands a time-step size smaller than the minimum, SWIFT will abort with an error message. This is a safe-guard against simulations that would never -complete due to the number of steps to run being too large. +complete due to the number of steps to run being too large. Note that in +cosmological runs, the meaning of these variables changes slightly. They do not +correspond to differences in time but in logarithm of the scale-factor. For +these runs, the simulation progresses in jumps of +:math:`\Delta\log(a)`. ``dt_max`` is then the maximally allowed change in +:math:`\Delta\log(a)` allowed for any particle in the simulation. This behaviour +mimics the variables of the smae name in the Gadget code. When running a non-cosmological simulation, the user also has to provide the time of the start and the time of the end of the simulation: -- GitLab