# Defining And Using Functions - HP 50g User Manual

Graphing calculator.

## Defining and using functions

Users can define their own functions by using the DEFINE 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 function
H(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
calculator. This programming language is called UserRPL (See Chapters
20 and 21 in the calculator's user's guide). The program shown above is
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