Hp 39g+ User manual

hp calculators

hp 39g+

& hp 39g/40g

GraphingMadeSimple

The purpose of this section of the tutorial is to

illustrate the graphing process in the Function

aplet at its most basic. More detailed examples

are given later.

•Step 1: Choose an Aplet

•Step 2: Enter a Function

•Step 3: PLOT

•Step 4: Adjust Axes

•A table of values

The materials presented on this page are adapted from material published by Applications in Mathematics. Materials presented on this page are licensed exclusively to

Hewlett-Packard Co.(“HP ”) by Applications in Mathematics, solely for viewing in this form and on this HP web site. Printing, reproduction or re-transmission in any other form

hp calculators

hp 39g+ G

& hp 39g/40g

Step 1: Choose an Aplet

The choice of aplet to use when graphing depends on the type of function. There are

three primary aplets provided for graphing – the Function aplet, the Polar aplet and

the Parametric aplet. In addition to those three, most of the other aplets have some

kind of graphical display to one degree or another.

If you have a rule of the form

(

)

22fx x

−or

yx=+

then you should use the Function

aplet. Notice that there is no need to enter

the “

()

x=” portion.

A polar equation is of the form

(

)

. If you

have a rule of this type then you should use

the Polar aplet.

Parametric equations are rules where both x

and yare functions of a third parameter t.

The graph shown right has the equation

() ()

(

)

5sin 3sin 11

() () ( )

5cos 3cos 11

yt t t

⎪

⎨=+

⎪

⎩

t⎧

Although other aplets have plot views, such

as the Statistics, Inference and Sequence

aplets shown right, they may not be the

primary focus of the aplet in the way that they

are for Function, Polar or Parametric.

The materials presented on this page are adapted from material published by Applications in Mathematics. Materials presented on this page are licensed exclusively to

Hewlett-Packard Co.(“HP ”) by Applications in Mathematics, solely for viewing in this form and on this HP web site. Printing, reproduction or re-transmission in any other form

hp calculators

hp 39g+ G

& hp 39g/40g

Step 2: Enter a Function

The SYMB (Symbolic) view is usually used to enter equations and functions. Simply

type your expression and press ENTER or OK. To overwrite an existing entry press

DEL or just type over it. Press SHIFT CLEAR to delete all functions. The SYMB view

for the Function aplet is shown but others are similar.

The button is normally used to enter Xin an expression

(Tor in other types of equations). Using ALPHA is also

possible, as is using screen key 3 (see right).

The mark next to the function determines whether the function is to be graphed or

ignored. Use (screen key 2) to add or remove the mark.

MATH functions can be used within expressions (see The

MATH Menu) and one function can reference another.

Highlighting an expression and pressing EVAL

(evaluate) will produce a simplified version if an

expression contains a reference to another function.

See right for two examples.

Tip: This can also be used to copy

an expression. To copy F1(X) to

F3(X) just set up F3(X)=F1(X) then

highlight and EVAL.

The materials presented on this page are adapted from material published by Applications in Mathematics. Materials presented on this page are licensed exclusively to

Hewlett-Packard Co.(“HP ”) by Applications in Mathematics, solely for viewing in this form and on this HP web site. Printing, reproduction or re-transmission in any other form

hp calculators

hp 39g+ G

& hp 39g/40g

Tip: This step size will change if

the axes are adjusted and may not

be a ‘nice’ number.

See Adjust Axes.

Step 3: PLOT

Just press PLOT to produce a graph. If the

result is not clear and the next step may be to Adjust Axes.

The coordinates of the current position are displayed. Although it may not be immed-

iately obvious, a small cross (circled) marks the cursor. Pressing and will move

the cross along the currently selected graph in steps of 0.1.

The initially selected graph is always the first one which

has a mark in the SYMB view. Pressing (or )

will move to the next graph which has a mark in the

SYMB view.

If you are not sure which graph is which then

press the MENU button (screen key 6) and

then press DEFN (screen key 5).

To jump to a specific point, press the GOTO button

(screen key 3). This will request a value and display

coordinates for that point. The value specified need

not be currently on the screen and can be the result of a

calculation such as √e.

To move the cross independently of the graphs, press TRACE (screen key 2). The

default is to have TRACE selected ( ).

The materials presented on this page are adapted from material published by Applications in Mathematics. Materials presented on this page are licensed exclusively to

Hewlett-Packard Co.(“HP ”) by Applications in Mathematics, solely for viewing in this form and on this HP web site. Printing, reproduction or re-transmission in any other form

hp calculators

hp 39g+ G

& hp 39g/40g

Step 4: Adjust Axes I

If the default set of axes are not satisfactory then press

SHIFT PLOT to access the PLOT SETUP view shown right.

Enter the minimum and maximum values for the axes as

XRNG and YRNG. The values of XTICK and YTICK control the

‘ticks’ on the axes. See the

difference shown right for

an example.

As can be seen right, there is a band at the bottom of the

screen which is use to display coordinates and the function

MENU. Pressing MENU once will display the list of function

tools. Pressing it again will display the graph on the entire

screen. Pressing a third time goes back to the coordinate

display.

YTick=1

YTick=10

Tip: To ensure that the band of plot tools does not hide

part of the graph try to include a certain amount of extra

length at the lower end of the y axis. A rough rule is to

include an extra one seventh of the true requirement.

For example, if you need to display –10 to 60 then you

should extend by 10 to –20 (1/7th of –10 to 60 is 10).

The materials presented on this page are adapted from material published by Applications in Mathematics. Materials presented on this page are licensed exclusively to

Hewlett-Packard Co.(“HP ”) by Applications in Mathematics, solely for viewing in this form and on this HP web site. Printing, reproduction or re-transmission in any other form

hp calculators

hp 39g+ G

& hp 39g/40g

Step 4: Adjust Axes II

Two extra tools are provided for use in adjusting axes. These are Auto scale and

ZOOM. Auto scale is found on the VIEWS menu and it automatically finds a y axis

scale which will display the entire graph for the x axis you have chosen. Auto scale

always scales on the first function with a mark in the SYMB view.

For example, using the previously defined functions…

An x axis of –4

to 4 gives….

… but an x axis of –10 to 10 gives the

less satisfactory result shown right,

where the y axis is far too long.

It is usually a good idea to go back to PLOT SETUP after Auto scaling and ‘clean up’

the choice. Clearly it still helps to have some idea of the shape of the function before

graphing it!

The ZOOM functions are available in

the PLOT view by pressing MENU,

then ZOOM. The Box option is the

one most often used to zoom in, but in

the example shown right, the Y-Zoom Out option

was used to obtain a better choice for the y axis.

The default is to zoom in or out by a factor of 4.

The materials presented on this page are adapted from material published by Applications in Mathematics. Materials presented on this page are licensed exclusively to

Hewlett-Packard Co.(“HP ”) by Applications in Mathematics, solely for viewing in this form and on this HP web site. Printing, reproduction or re-transmission in any other form

hp calculators

hp 39g+ G

& hp 39g/40g

A table of values

It is often helpful to display a table of values for your function.

On the hp 39g+, just press NUM to enter the Numeric view.

Press or to scroll through the list. Alternatively, simply type in a value and press

ENTER to have the list jump directly to that value.

If the step size for the table is not satis-

factory then press SHIFT NUM to enter the

NUM SETUP view. Change the value of

NumStep to any desired step size.

Changing the NumType from Automatic to

Build Your Own allows you to enter any

values you choose into the table.

Pressing BIG (screen key 4) will display the values using a

larger font.

The materials presented on this page are adapted from material published by Applications in Mathematics. Materials presented on this page are licensed exclusively to

Hewlett-Packard Co.(“HP ”) by Applications in Mathematics, solely for viewing in this form and on this HP web site. Printing, reproduction or re-transmission in any other form