HP 39gs_40gs_Mastering The Graphing Calculator_English_E_F2224-90010

The SYMB, PLOT and NUM keys

The

APLET key is used to choose between the various different aplets

available. Everything in the calculator revolves around aplets, which you can

think of either as miniature programs or as environments within which you can

work.

The hp 39gs and hp 40gs come with twelve standard aplets - Finance,

Function, Inference, Parametric, Polar, Linear Solver, Triangle Solver,

Quadratic Explorer, Sequence, Solve, Statistics and Trig Explorer.

Which one you want to work with is chosen via the

APLET key. See

page

14 for more details on this.

Calculator Tip

HOME too. See page 28.

The name of the active aplet is shown at the top of the screen, as

above. It is important to bear this in mind because the angle and

numeric settings are tied to the active aplet. Changing aplets may

therefore cause these settings to change in

In addition to the standard twelve, covered in great detail in the chapters following, many more aplets are

available from the Internet written by other programmers. Once these are downloaded into your calculator

they can also be accessed via the

APLET key. For more detail on this type of aplet, see the brief summary

later in this section, and the chapter entitled “Programming the hp 39gs & hp 40gs” on page 255.

When working mathematically there are three ways that we view functions:

• symbolically, as an equation;

• numerically, as a table;

• graphically, as a graph in various formats.

The

SYMB, PLOT and NUM keys are intended to reflect this common

methodology. In most aplets the

PLOT view shows the graph, the

SYMB view shows the equations and the NUM view shows the

equations in tabular (numeric) format.