What is the easiest way of topping field values within the framework of the SIR example?

[Hanno Spreeuw]

Looking at the SIR model example what would be the easiest way to limit the values of one of the fields?

By means of evolution_rate the three fields s, i and r evolve.
What if one of those three fields cannot exceed some value because of some constraint?

Say that i cannot exceed some value alpha. So if i became larger than alpha it would have to be set equal to alpha.

How would you implement that?

[Hanno Spreeuw]

I guess one could use to_scalar for a ScalarField, like this:

j = i.to_scalar(lambda f: numpy.fmin(f,alpha))