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Variability and Subtyping

The variability of an expression governs the degree of freedom with which the expression may vary during simulation. Variability is a specific property but has clear connections with the notion of data type. The example classes below illustrates the subtyping and variability rules for declaration equations and normal equations.

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1
Constants

This is not allowed, since p1 + 2 is not a constant expression

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2
Simulation of Constants

Below the error message is shown, after trying to simulate the Constants model.

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3
ConstantsCorrect

This is correct, since p1 + 2 has the same variability as p1.

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4
Simulation of ConstantsCorrect

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5
TestEquations

The equation in TestEquations is not correct, since b is a discrete time and noEvent(x > 1) is a continuous time expression.

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6
Simulation of TestEquations

Below the error message is shown, after trying to simulate the TestEquations model.