Time input parameters (parameter -- description -- options, with default given first):

ntstep -- number of transport time steps in TRINITY simulation -- default 20
niter -- max number of Newton iterations per time step -- default 1
ntdelt -- initial size of transport time step -- default 0.01
ntdelt_max -- maximum size of transport time step -- default 0.1
impfac -- time centering (1=implicit, 0=explicit) -- default 0.5
errtol -- maximum allowed relative error upon end of Newton iteration -- default 2.e-1
errflr -- relative error below which we stop iterating -- default 5.e-3 flrfac -- if relative error below errflr/flrfac, decrease ntdelt by factor of 2 -- default 2.0