A-24
TI-82/TI-83 Graphics Calculators
Copyright © Houghton Mifflin Company. All rights reserved.
On the
STAT PLOTS
screen, press
ENTER
to display
the
Plot1
screen, press
ENTER
to turn
Plot1 “On”,
and
select the options shown on the right.
(You can choose any of the three marks at the bottom
of the screen.)
Press
ZOOM
9
(
ZoomStat
) to have the calculator set
an autoscaled view of the data and draw the scatter plot.
(
ZoomStat
does not reset the
x
and
y
-axis tick marks.
You should do this manually with
WINDOW
if you
want different spacing between the marks.)
Press
Y=
. Notice that Ò
Plot1”
at the top of the screen
is now dark. This is because you have turned
Plot1
ÒonÓ.
If you always put input data in list
L
1
and output data
in list
L
2
, you can turn the scatter plots off and on from
the
Y=
screen rather than the stat plots screen from this
point on.
To turn
Plot1
off, use
to move the cursor to the
Plot1
position, and press
ENTER
. Reverse the process to turn
Plot1
back on.
A scatter plot is turned
on
when its name on the
Y=
screen is darkened.
¥ TI-83 lists can be named and stored in the calculatorÕs memory for later recall and use. I f
you do this and use the list by its stored name, you must use the name of the list in the stat
plot setup or on the stat plot screen each time you change lists. Refer to Section 1.4.13 of
this
Guide
and your
TI-83 Guidebook
for details.
1.4.6 FINDING FIRST DIFFERENCES
When the input values are evenly spaced, use
program
DIFF
to compute first differences in the output values. If the data are perfectly
linear (
i.e.
, every data point falls on the graph of the line), the first differences in t h e
output values are constant. If the first differences are ÒcloseÓ to constant, this is an
indication that a linear model
may
be appropriate.
Program
DIFF
is given in the TI-82/TI-83 Appendix.
To run the program, press
PRGM
followed by the
number of the location of the program and press
ENTER
. The message on the right appears on your
screen.
(We use the information in
L
4
and
L
5
in the next
chapter.)