__dt

The scenario's step size — for example, 1.0 if start and end times are in months and dt is 1, or 1/12 if start and end are in years and you're stepping monthly. Use it to scale rates that are expressed per unit of natural time, so a formula stays correct even if the scenario's granularity changes later.

__dt : number  (scope variable)

// Population growth scaled by step size
agent.get_prop("population", -1) * (1.0 + 0.02 * __dt)

// Continuous decay
agent.get_prop("signal", -1) * exp(-0.1 * __dt)