Defining And Using Functions - HP 48gII User Manual

Graphing calculator.

Defining and using functions

Users can define their own functions by using the DEF command available
thought the keystroke sequence „à (associated with the 2 key). The
function must be entered in the following format:
Function_name(arguments) = expression_containing_arguments
For example, we could define a simple functionH(x) = ln(x+1) + exp(-x).
Suppose that you have a need to evaluate this function for a number of
discrete values and, therefore, you want to be able to press a single button
and get the result you want without having to type the expression in the right-
hand side for each separate value. In the following example, we assume you
have set your calculator to ALG mode. Enter the following sequence of
keystrokes:
„à³~h„Ü~„x™‚Å
‚¹~„x+1™+„¸~„x`
The screen will look like this:
Press the J key, and you will notice that there is a new variable in your soft
menu key (@@@H@@). To see the contents of this variable press ‚@@@H@@. The screen
will show now:
Thus, the variable H contains a program defined by:
<<
x 'LN(x+1) + EXP(x)' >>
This is a simple program in the default programming language of the HP 48
G series, and also incorporated in the HP 49 G series. This programming
language is called UserRPL. The program shown above is relatively simple
and consists of two parts, contained between the program containers << >>:
Page 3-34