Configuring the Variables

Double-click the Optimization component icon .

The Optimization Component Editor appears.

From the Optimization Component Editor, click the Variables tab.

The list of parameters includes all input and in/out parameters from the Optimization component and parameters of the same modes from the subflow components, if they are not mapped to any parameters of the Optimization component.

Right-click in the table to access various options for working with variables.

For more information, see Setting Table Options.

Perform the following actions, which may vary based on your model design:

1. Determine which parameters you want to use as variables by selecting the corresponding check boxes in the first column. Alternatively, you can click Check to add all the selected parameters (including array elements) as design variables. To clear all the parameters, click Uncheck.

   If no parameters are selected, you will be prompted to add all parameters as design variables.

   Selecting a subflow parameter as a variable will, at a later time, create a corresponding parameter in the Optimization component. Only real, integer, and string parameters can be variables.

2. Specify the Lower Bound for the variables in the corresponding column. If you do not specify lower bound values, Isight uses the default value –1e15. This results in a large range for the design variables and may reduce the chances of finding a good design. It is recommended that you specify lower bounds for all variables. This setting is required if you are using the automatic scaling component preference. For more information, see Setting Optimization Component Preferences.
3. Change the initial value in the Value column.

   Note: This column is not available for the Multi-Island Genetic Algorithm because the initial design point is not used by this algorithm.

   Warning: The initial values of the variables are overridden at execution time if the Optimization component is a child component of another process component (e.g., a Task component). Therefore, to change the initial values of variables, you must change the corresponding parameter values in the parent (Task) component.

   Changing initial values of variables changes their values in the main Design Gateway window. These changes are immediate and cannot be reversed by clicking Cancel on the Optimization Component Editor.

4. Specify the Upper Bound for the variables in the corresponding column. If you do not specify upper bound values, Isight uses the default value +1e15. This results in a large range for the design variables and may reduce the chances of finding a good design. It is recommended that you specify upper bounds for all variables. This setting is required if you are using the automatic scaling component preference. For more information, see Setting Optimization Component Preferences.
5. Type a list of allowed values in the Allowed Values column, separated by a semicolon. If you enter allowed values, the lower and upper bounds are erased and vice versa. Entering a list of allowed values creates a discrete variable and the Optimization component uses only these values during optimization. The optimization algorithm will view this variable as an integer parameter with the range of values $0,1,2,\mathrm{...},N-1$, where $N$ is the length of the allowed values list.
6. Set the Scale Factor for the variable in the corresponding column. Scale factors are used to bring variable values to the same order of magnitude to improve the efficiency of the optimizers.

   Note: This column does not appear if you use the automatic scaling component preference. For more information, see Setting Optimization Component Preferences.

7. (Multi-Island Genetic Algorithm technique only) Set the value in the Gene Size column. This value controls the number of bits $N$ in all genes used for encoding the value of each variable. Every bit of the gene can change its value between 0 and 1. The total number of possible combinations in every gene is then $2N$. This number of combinations determines the minimum change in the value of any design variable during all genetic operations—take the allowed range of values for a design variable and divide it by the total number of combinations. To increase the minimum change in design variable values (i.e., to decrease the number of possible bit combinations when the allowed range of design variable values is small), decrease the gene size.

If desired, click Edit at the bottom of the editor to set attribute values for multiple design variables.

For more information, see Editing Attributes for Multiple Parameters.

If desired, map any of these variable attributes to parameters.

For more information, see Mapping Options and Attributes to Parameters.

Click OK to save your changes and to close the Optimization Component Editor.