CAGE User's Guide

Adding Variable Items

To add variable items you can use the Variable Dictionary toolbar, shown, or you can select items from the File -> New -> Variable Items menu.

Adding a Variable

To add a variable:

1. Select File -> New -> Variable Item -> Variable.

1. A new variable is added to the variable dictionary.

2. Select Edit -> Rename to alter the name of the variable.
3. Specify the Minimum and Maximum values of the variable in the edit boxes in the lower pane.
4. Specify the value of the Set Point in the edit box.

Using Set Points in the Variable Dictionary.   The set point of a variable is a point that is of particular interest in the range of the variable.

For example, for the air-fuel ratio variable, AFR, the range of values is typically 11 to 17. However, whenever only one value of AFR is required, it is preferable to choose 14.3, the stoichiometric constant, over any other value. So enter 14.3 as the Set Point.

CAGE uses the set point as the default value of the variable wherever one value from the variable range is required. For instance, CAGE uses the set point when evaluating a model over the range of a different variable.

For example, a simple model for torque depends on AFR, engine speed, and relative air charge. CAGE uses the set point of AFR when it calculates the values of the model over the ranges of the engine speed and relative air charge.

Adding a Constant

To add a constant:

1. Select File -> New -> Variable Item -> Constant.

1. A new constant is added to the variable dictionary.

2. Select Edit -> Rename to alter the name of the constant.
3. Specify the value of the constant in the Set Point edit box, in the lower pane.

Adding Formulas

You might want to add a formula to your session. For example, the formula

where afr is the air-fuel ratio and stoich is the stoichiometric constant.

To add a formula:

1. Select File -> New ->Variable Item -> Formula.

1. The Add Formula dialog box appears.

2. In the dialog, enter the right side of the formula, afr/stoich, and click OK.

1. A new formula is added to the variable dictionary.

3. Select Edit -> Rename to alter the name of the formula.

Note    Formulas can only have one variable.

See Also

• Setting Up Your Variable Items
• Adding Variable Items

Setting Up Your Variable Items

Using the Variable Menu