Appendix A - Part 1 of 3

Appendix A: Language Summary

In the following descriptions, the name of each Analytica object is in Bold face, and Analytica concepts or terms without corresponding objects are in italic. Optional parameters are enclosed in [ ...]. In general, if you omit the main parameter of a command, Analytica will assume you mean the current object (i.e., the last object explicitly mentioned). If you omit the last parameter of a function such as Sum, Min, or Max, whose second parameter is an optional index specifying the dimension of a multi-dimensional array over which to perform the operation, Analytica will assume the outermost dimension.

Attributes

Attributes fall under the following categories:

• User-specified attributes - attributes that can be created and/or modified by the user. You assign a value v to an attribute a of object o with the following syntax: a o: v. In general, to display an attribute of a particular object you use the syntax a o.

• Computed attributes - attributes that are computed by Analytica.

• User Interface attributes - attributes that are set by visual manipulation in the Analytica user interface.

User-specified Attributes

Author
The author(s) of a model or another object. By default, this is the computer’s registered user name (on Macintosh, specified in the Sharing Setup control panel).

Title
Brief text used to identify a variable. Titles can be up to 255 characters; however Analytica often truncates them to fit.

Description
One or more lines about what an object represents. Descriptions will help you - and other people who access the model - understand it.

Definition
An expression that Analytica uses to compute the value of an object. A definition may be a simple number, an array, a probability distribution or a mathematical Expression that includes other variables. Definitions may be several lines long.

Units
The units of measurement of a variable, e.g., $/yr. You can leave the Units field blank if the variable is a number or a dimensionless ratio.

Parameters
When you create a new mathematical Function, you may specify a list of parameters for each Function. User-defined functions are described in the Analytica Reference.

Check
A test that Analytica conducts on the validity of the value of a variable. A Check attribute is an Expression that contains the variable to be tested. If checking evaluates to False (or 0), Analytica warns you that the value of the variable is questionable. Check attributes are described later in this manual.

Usecheck
An attribute that controls whether a variable will (or won't) be checked for legality according to its Check attribute whenever it is evaluated. Usecheck overrides the system variable Checking for the particular variable to which it is attached.

Script
An attribute that contains a sequence of commands, each separated by carriage returns, that are executed when the user clicks on the button containing the script.

Balloonhelp
An attribute that contains help that appears when the mouse is over the object's node in a Diagram window. By default, Analytica uses the Description attribute for an object in Balloon Help. This attribute is only available on the Macintosh.

Indexvals
An attribute that may be defined as a list or list of labels, and function as a Self index for a variable table definition. This attribute is normally set by Analytica, but can be user-specified.

Domain
An attribute that may be defined as a list or list of labels, and function as a Self domain for a variable probtable definition. This attribute is normally set by Analytica, but can be user-specified.

Computed Attributes

Date The data the model was created. Savedate The last time the model was saved. Saveauthor The user who last modified a model, if different from the owner of the computer on which the model is created. Inputs A list of variables and functions that appear in the definition of the specified variable or function. Outputs A list of variables and functions that refer to this object in their Definitions. Value The deterministic value of a variable. Probvalue The probabilistic value of a variable. Contains The list of variables and other objects created within a model. Isin The model to which an object belongs.