dymola - How does an abruptly input impact the simulation in Modelica

Question

i want to know how does an input that change abruptly can impact the simulation, and which one is better to use an abrupt input or an input that change smoothly here are to pictures for a better understanding an abrupt input

an input that changes smoothly

hope that someone can answer my question

Answer 1

A smooth input is generally faster than an "abruptly changing one", especially if they are as clear as above.

However, it is not always this easy and I would say that there are four cases, with the most preferable one first:

1. Smooth signal as above
2. Abrupt signals similar as above with an event for each change.
3. Abrupt signal as above without events; typically you see that these changes are very steep lines and not horizontal - and that might be the case in the diagram above.
4. Signals without events that are smooth in the mathematical sense (although not analytical), but in practice changes so unexpectantly that the solvers cannot handle them.