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13 Expressions

The system uses expressions in parameters and in simulation rules. Expressions include mathematical and logical formulas. Expressions can be a simple as 1+2; they can use another parameter as in Age +1; They can be complex expressions using mathematical functions as in Exp(-Age); They can even use if statements as in Iif(Gr(Age+1,50),1,0); These expressions can also represent tables as in Table(1,3,0,0.5,1,Age,NaN,20,30,40) . These formulas may contain, as literals parameter names (including parameters that hold values, parameters that specify user defined functions, state indicator names, and some reserved words), mathematical operators, system built in functions. Below is a list of allowed operators:

13.1 Supported arithmetic functions

13.2 Other supported literals

13.3 A list of comparison operators

13.4 A list of Boolean operators

In the following Boolean operators, the results are either 1 or 0. Any argument that not zero is considered be true and zero is treated as false.

13.5 A list of special math related functions and symbols

Note that these may be platform dependent. Boolean operators treat NaN (Not a Number) as false as well as any other non-number type such as a vector/matrix.

13.6 Mathematical functions

13.7 Other functions

13.8 Statistical Distributions - Random number generators

Note the difference in number of arguments from the CDF shown in the next section. These random functions can be used to define the Distribution of parameters:

13.9 Statistical Distribution - CDF evaluation at point x

Note the difference in number of arguments from the random functions shown in the section above. The last argument x represents the value at which the CDF will be calculated. These functions cannot be used to define the Distribution of parameters:

13.10 Control and Data Access

13.11 Application specific

Note that missing values are not supported by the system. An exception is population data upload in which case missing data values are ignored by default in simulation.