# App Functions And Variables - HP NW280-200X User Manual

Prime graphing calculator.

## App functions and variables

Functions
An introduction to HP apps
open it. You will see in it all the same views and options as
in the parent app.
In this example we have used the Fibonacci series as a potential
topic for a customized app. To see how to create the Fibonacci
series once inside the Sequence app—or an app based on the
Sequence app—see chapter 16, "Sequence app", beginning on
page 257.
As well as cloning a built-in app—as described above—you can
modify the internal workings of a customized app using the HP
Prime programming language. See "Customizing an app" on
page 460.
App functions are used in HP apps to perform common
calculations. For example, in the Function app, the Plot view Fcn
menu has a function called SLOPE that calculates the slope of a
given function at a given point. The SLOPE function can also be
used from the Home view or a program.
For example, suppose you want to find the derivative of x
x = 2. One way, using an app function, is as follows:
1. Press
.
D
2. Tap
and select Function > SLOPE.
SLOPE() appears on the entry line, ready for you to specify
the function and the x-value.
3. Enter the function:
Asjw
4. Enter the parameter
separator:
o
5. Enter the x-value and press
E
.
The slope (that is the
derivative) at x = 2 is
calculated: 4.
All the app functions are described in "App menu", beginning on
page 312.
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