Specifying the default value for variables and plug-in functions

When the software evaluates the formula for an expression outside the context of a field, it assigns a numerical value to the variables and plug-in functions that are included in the formula. Examples of when the software evaluates the formula for an expression outside of the context of a field include the following:

• Creating an expression in the Expressions dialog box

• Entering a formula in the Formula Field dialog box

The numerical values that the software assigns to the variables and plug-in functions can produce errors that prevent the expression or field from being created. You can avoid some errors by specifying the numerical value that the software assigns to variables and plug-in functions.

For example, suppose that in the Expressions dialog box, in the Formula column, you enter 1/(x/1[mm]-1). If the software assigns 1[mm] as the value for x, a divide by zero error occurs.

Note:

In the Expressions dialog box, the numerical value and base unit that the software assigns to variables and plug-in functions are displayed in the Value and Units columns, respectively.

To change the numerical value, in the Named Variables dialog box, from the Unset Variable Value Option list, select one of the following options:

• Default — Evaluates the expression with the system variables and plug-in functions equal to 1 [base unit].

• Undefined Value — Evaluates the expression with the system variables and plug-in functions equal to 2 x 1019 [base unit].

• As Specified — Evaluates the expression with the system variables and plug-in functions equal to V [base unit], where V is the numerical value that you type in the box.

Thus, in the example, if you select Undefined Value from the Unset Variable Value Option list, or you select As Specified from the Unset Variable Value Option list and specify a numerical value other than 1, the divide by zero error is avoided. You can then use the expression in the definition of a load, constraint, and so on.

Note:

The numerical value that you select from the Unset Variable Value Option list is assigned to plug-in functions that are provided with the software. It is not assigned to customer-provided plug-in functions.

Where do I find it?

Application	Pre/Post
Simulation Navigator	Right-click the Fields node→Named Variables
Location in dialog box	Options group→Unset Variable Value Option list

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Using unit normal vector components as variables in expressions

Special consideration when importing expressions

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Specifying the default value for variables and plug-in functions, Simcenter 3D 2021.1 Series

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