If you call a Simulink® function from multiple sites in a chart, all call sites share the state of the function variables. For example, suppose you have a chart with two calls to the same Simulink function at each time step.
a block diagram that increments a counter by 1 each time the function
At each time step, the function
f is called
twice, which causes the counter to increment by 2. Because all call
sites share the value of this counter, the data
by 2 at each time step.
This behavior also applies to external function-call subsystems in a Simulink model. For more information, see Using Function-Call Subsystems (Simulink).