Define a Discrete Input Variable and Set the Number of Points
A discrete variable is an input variable that can take values from an orderable finite list of numeric values, for example x = 0.1, 0.2, 0.3, or 0.4.
 In the Define Input Variables step, click the Modes tab.

In the Mode column for the input variable you are defining, select
Discrete.
Note: The Values cell turns orange, which indicates you can edit its values.
 In the Values cell, click .

In the dialog, edit the discrete value set and then click OK.
 To add content to this set, click Add Row; to remove content from this set, click Remove Row.
 To divide the value range into equal segments, change the lower and upper bounds, enter a value in the Step Number field, and then click Set.
 To create a set with equal step sizes, change the lower and upper bounds, enter a value in the Step Size field, and then click Set.