HP Prime Graphing Wireless Calculator Instrukcja Użytkownika Pobierz pdf (Strona 517)

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23 Variables

Variables are objects that have names and contain data. They are used to store data, either for later use or to

control settings in the Prime system. There are four types of variables, all of which can be found in the Vars

menu by pressing :

●

Home variables

●

CAS variables

●

App variables

●

User variables

The Home and app variables all have names reserved for them. They are also typed; that is, they can contain

only certain types of objects. For example, the Home variable A can only contain a real number. You use Home

variables to store data that is important to you, such as matrices, lists, real numbers, etc. You use app

variables to store data in apps or to change app settings. You can accomplish these same tasks via the user

interface of an app, but app variables give you a quick way of doing these tasks, either from Home or within a

program. For example, you can store the expression “SIN(X)” in the Function app variable F1 in Home View,

or you could open the Function app, navigate to

F1(X), and enter SIN(X) in that eld.

CAS and user variables can be created by the user and they have no particular type. Their names may be of

any length as well. Thus, diff(t2,t) returns 2*t and diff((bt)2, bt) returns 2*bt for the CAS

variables t and bt. Further evaluation of 2*bt will only return 2*bt, unless an object has been stored in bt.

For example, if you enter

bt:={1,2,3} and then enter diff((bt)2, bt), the CAS will still return

2*bt. But if you evaluate that result (using the EVAL command), the CAS will now return {2,4,6}.

User variables are explicitly created by the user. You create user variables either in a program or by

assignment in Home view. User variables created in a program are either declared as local or exported as

global. User variables created by assignment or exported from a program will show up in the Vars User menu.

Local variables exist only within their own program.

The following sections describe the various processes associated with variables, such as creating them,

storing objects in them, and retrieving their contents. The rest of the chapter contains tables that list all the

Home and app variable names.

Working with variables

Working with Home variables

Example 1: Assign π

to the Home variable A and then calculate 5*A

Press to display Home view.

Assign π

to A:

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