tolerance property
getter/setter pair
How close to the actual end of the simulation a value at a particular time must be before isDone considers the simulation to be "done".
A simulation with an asymptotic curve would never technically be "done", but once the difference from the value at a particular time and the asymptote itself could not be seen, it would be pointless to continue. The tolerance defines how to determine if the difference could not be seen.
Implementation
Tolerance tolerance;