HP 38g - Graphing Calculator Instruction Manual

HP 38G
FREQUENTLY ASKED QUESTIONS Page 1of 3
Keystrokes in this document are shown in two different formats. Commands accessible on the keyboard are
shown as symbols, such as •, or within square brackets, such as [SPACE]. Commands accessible through menus
are shown between vertical bars, such as |CHOOS|.
Several of the commands and variables may be entered in one of two ways: either spell the word or recall it from
a built-in menu. For example, to enter the variable TIME:
1. Press and hold the [A...Z] key.
2. Press the letters TIME.
3. Release the [A...Z] key.
OR
1. Press the ”key.
2. Use the hkey to highlight the “Modes” title.
3. Press igto highlight “Time.”
4. Press the |OK| menu key to enter the command.
Q: Why does the ((Ÿ)) annunciator stay on, even
after the calculator is turned off?
A: This indicates a low battery condition in the
calculator. The HP 38G uses three AAA batteries.
Q: Where can I find batteries for my calculator?
A: The batteries should be available at most
convenience or department stores. Select three AAA
batteries of any brand, but make sure they are all of
the same brand and type. NiCad batteries are not
recommended because of their low capacity and
short low-battery warning time.
Q: How do I change the number of decimal places
the calculator displays?
A: Press k[MODES] to enter the input form, then
hto highlight the “Number format” field. Press
|CHOOS|, then use the arrow keys to select the
desired format. If Fixed, Scientific, Engineering, or
Fraction is selected, a number indicating the number
of displayed digits will appear to the right of the
“Number format” field; simply arrow to this number
and type in the desired amount (up to 11).
Q: What does an “E” in a number (for example,
2.51E3) mean?
A: The “E” stands for exponent of ten. In the
example 2.51E3, the number is 2.51 × 10³, which
equals 2510.
Q: How do I adjust the contrast of the display?
A: Simultaneously press oand +to darken the
contrast, or simultaneously press oand -to
lighten the contrast.
Q: How do I set the date and time?
A: To set the date and time, store the correct
settings in the date and time variables. Use the
format M.DDYYYY for the date and H.MMSS for the
time. For example, to set the date as May 6, 1996:
1. If necessary, press •to enter the stack
environment.
2. In the command line, key in 5.061996, press the
|STOØ| menu key, then enter the variable DATE
(which is accessed by pressing ”|HOME|, then
scrolling to the “Modes” title).
3. Press •.
Q: How do I display the current date and time?
A: After setting the date and time as described
above, enter the command DISPTIME. The day,
date, and time will be displayed in a message box.
The message may be removed by pressing the |OK|
menu key or ….

HP 38G
FREQUENTLY ASKED QUESTIONS Page 2of 3
Q: How do I check the amount of available
memory?
A: The amount of memory available may be
displayed by using a SYSEVAL command, which is
not supported by Hewlett-Packard. Use this feature
carefully:
1. If you are not at the Home screen, press
[HOME].
2. On the edit line, key in: SYSEVAL 535863.
3. Press •. On the right side of the screen, the
bytes of available memory will be displayed.
Q: How do I reset a built-in Aplet after I have
made changes?
A: Resetting a built-in Aplet clears all of the User-
entered data for that Aplet and restores the default
settings:
1. Press [LIB] to display the Aplet Library.
2. Use the hkey to highlight the appropriate Aplet,
then press the |RESET| menu key. A message
box will appear asking whether the Aplet should
be reset; press the |YES| menu key.
Q: How do I print the display of a plot?
A: While viewing a plot (or any) display, you may
send a copy of the display to the optional HP 82240B
Infrared Printer:
1. Press [SYMB], then highlight and check the
function(s) desired.
2. Press ¥to view the graph.
3. Press and hold the okey, press and hold the
¥key, then simultaneously release both keys.
This procedure will perform a “screen capture”
and store it in variable G0 (G zero).
4. Place the HP 38G and the infrared printer no
farther than two inches apart. Align the HP 38G
and the infrared printer such that the arrow mark
(near the Hewlett-Packard logo just above the
display) on the HP 38G is aimed at the center of
the printer’s infrared window (located just below
the Hewlett-Packard logo).
5. If necessary, turn the infrared printer on.
6. Press •to return to the stack environment,
then enter the command PRVAR (under the
“Print” title of the PROGRAM COMMANDS
menu, which is accessed by pressing [MATH]
|CMDS|). Press [A...Z] G0•to execute the
command.
Q: Why do trigonometric functions give me
unexpected results?
A: The angle mode may be wrong for the particular
problem. Check the angle mode annunciator in the
upper left corner of the display screen; DEG means
degrees, RAD means radians, and GRD means
grads. To change the angle mode:
1. Press km.
2. While highlighting the “Angle Measure” field,
press the |CHOOS| menu key.
3. Highlight the desired mode, then press the |OK|
menu key.
Q: When I take the sine of π, I do not get zero;
why not?
A: There are two possibilities. First, the calculator
may not be in radians mode. If the RAD annunciator
is not displayed in the upper left corner of the screen,
change the angle mode as described in the previous
question. Regardless, the HP 38G, like all
calculators, can only compute using a finite number
of decimal places. Because πcontains an infinite
number of decimal places, any results involving π
must necessarily be rounded. In this case, the
rounded number differs from the theoretical answer
by approximately one part in 10 E-12.
Q: How do I reset the calculator?
A: To erase everything you have stored in the
calculator and restore the factory-default settings:
1. Press and hold o.
2. Press and hold the leftmost top-row key and the
rightmost top row key so that all three keys are
pressed simultaneously.
3. Release all three keys.
Q: How do I program the HP 38G?
A: The programming chapter of the HP 38G User’s
Guide discusses creating and editing programs,
lists various program commands, and contains
some short examples. For more information,
please visit our Web site on the Internet at:
http://www.hp.com/calculators.

HP 38G
FREQUENTLY ASKED QUESTIONS Page 3of 3
Q: How can I take the LOG of a base other than
10?
A: If Y= LOGX(Z), then Y=LOG10(Z) ÷LOG10(X).
For example, the LOG2(8) is LOG10(8) ÷LOG10(2),
which is 3. The same formula applies to natural
logorithms.
Q: What if my calculator requires repair service?
A: Before submitting your unit for repair, please
contact our Calculator Support representatives at
970-392-1001 for trouble-shooting assistance. Our
phone lines are open 8:00 a.m. to
5:00 p.m. Pacific Standard Time Monday through
Friday, excluding holidays.
Q: How can I get answers to other questions?
A: For further assistance, please visit our Web site
at http://www.hp.com/calculators. If you do not have
Internet access or prefer to speak with a support
representative, please contact our Handheld Product
Support department at 970-392-1001. Our phone
lines are open 8:00 a.m. to 5:00 p.m. Pacific
Standard Time Monday through Friday, excluding
holidays.
*Public Domain - Preliminary
Hewlett-Packard Company shall not be liable for any errors or for incidental or consequential damages in connection with the
furnishing, performance, or use of this publication or the procedures contained herein. This publication is subject to change
without notice. Last Rev. 10/2/98