| Ø | Open the Equation editor on target revenue. |
| Ø | Type "10000+" to begin the equation. |
| Ø | Click on the Functions Tab. |
| Ø | Select STEP from the list and press the Enter key. |
| Ø | Double click on {stime} in the equation. |
| Ø | Enter the units $/Month and click on OK. |
The final equation should read
target revenue=10000+STEP(5000,10)
The STEP function is one of the most commonly used input functions. This function returns 0 until Time reaches {stime} and then it returns {sheight}. In our example it will return 0 till time 10 then it will return 5000 so that target revenue will start at 10000, remain constant till time 10 and then jump to 15000. The STEP function is important because a step change is a very good way to get a model to show the behavior modes it can generate. For example in a supply chain model, you can use a step change in demand to take the supply
There are a number of functions related to the STEP function. PULSE, PULSE TRAIN, RAMP and the RANDOM... functions. All of these functions return a value that is different at different times. The RANDOM... functions return values that change randomly from time to time, though they will be the same from run to run so that you can replicate results.
Another common source of time varying behavior is Data - this is discussed in Chapter 16 "Using Data in Models."You can also use the variable Time as an input to other functions such as SIN to get different types of behavior.
