When I run it, it just gives a checkmark, no index value. When I plug it in to find the index, I get ArgumentError: invalid index: nothing of type Nothing I think this means the code of line ran successfully but did not find anything matching the criteria.
Looking at my difference values, I want to select the time step that is associated with -6.22e-10, but I don’t want to use that exact value as I need to repeat this selection process over other databases.
The purpose of finding this timestep is to approximate when a system becomes stable as the change in values of df.y becomes smaller and smaller.