HP-38G Graphic Calculator

Date: 08/29/98 at 11:36:52
From: Mr.R
Subject: Graphic calculator hp38g

I just bought an HP-38G. I've tried to graph some math problems, and 
they just won't graph. Mqybe you know about the HP-38G and can help 
me. I was trying to graph F(x) = 3x+2 or y = 4x+3.

Date: 10/22/98 at 13:53:46
From: Doctor Andrewg
Subject: Re: Graphic calculator hp38g

Hi Mr. R!

The HP-38G is a pretty amazing calculator, and graphing functions is a 
good way of understanding them. When you do calculus problems this can 
be really useful for checking derivatives (slopes), integrals (the 
area under the curve), and unusual parts of the graph.

That's enough advertising for Hewlett Packard - on to your question.  

If you follow these steps carefully, you will be able to draw these 
graphs.

I assume that you start in the HOME mode. This is where you normally 
do your calculations. If you are not already there then press the 
"HOME" button (you may need to press "OK" or "CANCEL" first if you are 
already doing something else).  

Now the graphing aplet is a library aplet (it's built in) - so press 
"LIB" and a screen with a list of six aplets should appear. The order 
that these appear in depends on which ones you used last (the HP-38G 
puts those ones at the top to make life easier for you in case you need 
them again). One of these aplets is the FUNCTION aplet. Move the cursor 
down to this one (using the arrow keys) and press "ENTER". The screen 
you are now in is the FUNCTION SYMBOLIC VIEW. If you have defined any 
functions already then they should appear here next to the F1(X)=, 
F2(X)=, etc. Go to one of these (any one will do, but F1(X)= should be 
where your cursor starts) and start typing in your function, say 3X+2. 
Just press "3", then "X", "+", and "2". You can enter the "X" by using 
the third function button on the top row of the calculator or by 
pressing "A...Z" and then "."  Now you should have 3X+2 at the bottom 
of the screen. If you press "ENTER" then it will be copied to the 
function number you were on and a tick mark will appear next to that 
function.  

If any other functions have tick marks next to them then you can remove 
these by moving to the function and pressing the second function button 
on the top row. You can graph more than one function at a time if you 
want by "ticking" more than one function. But we'll start off with just 
one graph - so untick all the other functions.

If you want to see that graph now, you need to press the "PLOT" button. 
The graph should be on the screen now! Sometimes it takes a few seconds 
for the HP-38G to plot the graph. To get back to the function screen 
where you entered the function press "SYMB". Pressing "NUM" will show 
you values of the function for different values of x.

One last hint. When you are in the plot view (after pressing "PLOT") 
you can press the sixth (rightmost) function button on the top row to 
bring up a menu. This lets you zoom in on the function and do other 
neat tricks.  

If the graphs still don't work for you then "reset" the function aplet 
by going back to the aplet library (press "LIB")  and press "DEL" when 
you are on the function aplet. The HP-38G will ask you to confirm that 
you want to reset the aplet - this deletes the functions you have 
defined and restores all of the options to their defaults. Say yes by 
pressing the sixth (rightmost) function button on the top row and try 
the steps I gave above again.

Good luck with your calculator - it is a very powerful tool to help you 
solve maths and statistics problems.  

Keep experimenting with your calculator - but try to avoid relying on 
it too much. You never know when your batteries will run out on your 
calculator - but your brain should be good for a lifetime!

- Doctor AndrewG, The Math Forum
  http://mathforum.org/dr.math/