Start and End Value Difference
Calculating the Difference Between Start and End Values of an Element
In this example, the change in volume of a pond or reservoir is computed. Discrete change elements are used to 'grab' the initial and final values of the Pond volume. One discrete change element triggers when the simulation starts and the other triggers when the elapsed time is equal to the simulation duration. The values of the discrete change elements are stored in Integrator Elements. An Expression Element is used to calculate the difference between final and initial volumes of the pond.