Dear all,
When I read propel.cc source file, I find when calculating the time-dependent propagation equation, for each time step, the computation would repeat 20 times, i.e. timestep_repeat = 20. I think the well-known Crank-Nicolson theme is unconditionally stable. Why does the computation repeat 20 times ?

Thank you very much for your reply.

Sorry for the late reply. The code is meant to repeat until a steady state solution at each timestep. Hence we need several iterations at each timestep.

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Gudlaugur Johannesson, GALPROP developer