This sets a fixed number of equilibrium iterations in each time step
(for time steps of the **control_timestep** record with the same index).
If *number_of_iterations* is 1 then the time stepping is
completely Euler explicit.
For larger values, the time stepping becomes implicit.
For many iterations, the time stepping is Euler implicit.
Typically, *number_of_iterations* is 1,2 or 3.
Default *number_of_iterations* is 2.

As an alternative, you can use **control_timestep_iterations_automatic**.

tochnog 2001-09-02