The Evl function is not a distribution. It is the simplest use of an Expression. This function supports a single line expression. That expression can contain System Attributes, Global (or User-defined) Attributes, System Methods and Operators (+, - , etc.). The Evl function can be found on any of the combo boxes where you find the standard distributions and User-defined Functions. See Chapter 10 of the User's Manual for further description.
Because such a broad range of values can be used in an Evl function, the Distribution Details dialog provides some entry aids. In any dialog where a list of distributions is available, press the ellipsis button (labeled "...") to see this dialog. At the top it will display the current value to be evaluated (e.g., "Evl(1.0)" will display "1.0"). Below that will be three separate combo boxes containing lists of items from which to choose, and a button labeled "Add Selection to Evl" that will place the current selection at the insertion point in the field at top.
Selection Lists
System Attributes
This list will initially be identified by the display of the value "---- System Attributes ----" as its first entry. It contains entries for each category of System Attribute:
-- Model: System Level attributes
-- EntityType: Entity Type attributes
-- Entity: Entity (instance) attributes
-- Resource: Resource attributes
-- Activity/Process: attributes pertaining to activities or processes
These correspond to the list in Appendix F of the SIMPROCESS User's Manual. With certain exceptions, all attributes of type INTEGER, REAL or OBJECT will appear on the list for selection, under their respective categories.
Global Attributes
This list will initially be identified by the display of the value "---- Global Attributes ----" as its first entry. It contains entries for each category of Global Attribute in the model having one or more defined attributes (see Define/Global Attributes):
-- Entity
-- EntityType
-- Resource
-- Activity
-- Model
All attributes of type INTEGER, REAL or OBJECT will appear on the list for selection under their respective categories. Categories with no defined attributes will not be present. Attributes designated as arrays will contain entries for each possible value of the array index.
System Methods
This list will initially be identified by the display of the value "---- System Methods ----" as its first entry. It contains entries for all System Methods defined in Appendix F of the SIMPROCESS User's Manual which return REAL or INTEGER values, as well as the Resource("").
Selecting an item that does not represent a "list type" (having "----" before and after the value) or a category (starting with "-- ") will cause all other lists to automatically change their selections to the "list type" selection, so that only one may have a valid selection at any time. Selecting any category name item (beginning with "-- ") will cause the selection to advance to the first item in that category.
When the "Add Selection to Evl" button is pressed with a valid selection, the text of that item will be placed in the field at the top of the dialog where the current insertion pointer is located. When the dialog is initially displayed, the insertion pointer is at the end of the current value in the field. If any text in the field was selected, then it will be replaced by the value from any list.
These lists are intended only as an aid to help in constructing a valid Evl function and do not ensure that it is syntactically or semantically correct or complete. Additional information may still need to be entered manually.