Add an indicator for stability or make it impossible to select unstable configurations

[RobinKa]

For example it is possible to select a timestep that will cause the simulation to diverge and lots of other parameters that can cause this. Perhaps add some visual indication for when the simulation is unstable, or a button for finding a stable configuration automatically.

[damian-666]

might consider https://www.josstam.com/reversible fixed point , or CFL condition

floats are a problem in basic algebra